initial commit, 4.5 stable

editor/scene/gui/SCsub

@@ -0,0 +1,6 @@
+#!/usr/bin/env python
+from misc.utility.scons_hints import *
+
+Import("env")
+
+env.add_source_files(env.editor_sources, "*.cpp")

editor/scene/gui/control_editor_plugin.h

@@ -0,0 +1,257 @@
+/**************************************************************************/
+/*  control_editor_plugin.h                                               */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#pragma once
+
+#include "editor/inspector/editor_inspector.h"
+#include "editor/plugins/editor_plugin.h"
+#include "scene/gui/box_container.h"
+#include "scene/gui/button.h"
+#include "scene/gui/margin_container.h"
+
+class CheckBox;
+class CheckButton;
+class EditorSelection;
+class GridContainer;
+class Label;
+class OptionButton;
+class PanelContainer;
+class PopupPanel;
+class Separator;
+class TextureRect;
+
+// Inspector controls.
+class ControlPositioningWarning : public MarginContainer {
+	GDCLASS(ControlPositioningWarning, MarginContainer);
+
+	Control *control_node = nullptr;
+
+	PanelContainer *bg_panel = nullptr;
+	GridContainer *grid = nullptr;
+	TextureRect *title_icon = nullptr;
+	TextureRect *hint_icon = nullptr;
+	Label *title_label = nullptr;
+	Label *hint_label = nullptr;
+	Control *hint_filler_left = nullptr;
+	Control *hint_filler_right = nullptr;
+
+	void _update_warning();
+	void _update_toggler();
+	virtual void gui_input(const Ref<InputEvent> &p_event) override;
+
+protected:
+	void _notification(int p_notification);
+
+public:
+	void set_control(Control *p_node);
+
+	ControlPositioningWarning();
+};
+
+class EditorPropertyAnchorsPreset : public EditorProperty {
+	GDCLASS(EditorPropertyAnchorsPreset, EditorProperty);
+	OptionButton *options = nullptr;
+
+	void _option_selected(int p_which);
+
+protected:
+	virtual void _set_read_only(bool p_read_only) override;
+	void _notification(int p_what);
+
+public:
+	void setup(const Vector<String> &p_options);
+	virtual void update_property() override;
+	EditorPropertyAnchorsPreset();
+};
+
+class EditorPropertySizeFlags : public EditorProperty {
+	GDCLASS(EditorPropertySizeFlags, EditorProperty);
+
+	enum FlagPreset {
+		SIZE_FLAGS_PRESET_FILL,
+		SIZE_FLAGS_PRESET_SHRINK_BEGIN,
+		SIZE_FLAGS_PRESET_SHRINK_CENTER,
+		SIZE_FLAGS_PRESET_SHRINK_END,
+		SIZE_FLAGS_PRESET_CUSTOM,
+	};
+
+	OptionButton *flag_presets = nullptr;
+	CheckBox *flag_expand = nullptr;
+	VBoxContainer *flag_options = nullptr;
+	Vector<CheckBox *> flag_checks;
+
+	bool vertical = false;
+
+	bool keep_selected_preset = false;
+
+	void _preset_selected(int p_which);
+	void _expand_toggled();
+	void _flag_toggled();
+
+protected:
+	virtual void _set_read_only(bool p_read_only) override;
+
+public:
+	void setup(const Vector<String> &p_options, bool p_vertical);
+	virtual void update_property() override;
+	EditorPropertySizeFlags();
+};
+
+class EditorInspectorPluginControl : public EditorInspectorPlugin {
+	GDCLASS(EditorInspectorPluginControl, EditorInspectorPlugin);
+
+	bool inside_control_category = false;
+
+public:
+	virtual bool can_handle(Object *p_object) override;
+	virtual void parse_category(Object *p_object, const String &p_category) override;
+	virtual void parse_group(Object *p_object, const String &p_group) override;
+	virtual bool parse_property(Object *p_object, const Variant::Type p_type, const String &p_path, const PropertyHint p_hint, const String &p_hint_text, const BitField<PropertyUsageFlags> p_usage, const bool p_wide = false) override;
+};
+
+// Toolbar controls.
+class ControlEditorPopupButton : public Button {
+	GDCLASS(ControlEditorPopupButton, Button);
+
+	Ref<Texture2D> arrow_icon;
+
+	PopupPanel *popup_panel = nullptr;
+	VBoxContainer *popup_vbox = nullptr;
+
+	void _popup_visibility_changed(bool p_visible);
+
+protected:
+	void _notification(int p_what);
+
+public:
+	virtual Size2 get_minimum_size() const override;
+	virtual void toggled(bool p_pressed) override;
+
+	VBoxContainer *get_popup_hbox() const { return popup_vbox; }
+
+	ControlEditorPopupButton();
+};
+
+class ControlEditorPresetPicker : public MarginContainer {
+	GDCLASS(ControlEditorPresetPicker, MarginContainer);
+
+	virtual void _preset_button_pressed(const int p_preset) {}
+
+protected:
+	static constexpr int grid_separation = 0;
+	HashMap<int, Button *> preset_buttons;
+
+	void _add_row_button(HBoxContainer *p_row, const int p_preset, const String &p_name);
+	void _add_separator(BoxContainer *p_box, Separator *p_separator);
+};
+
+class AnchorPresetPicker : public ControlEditorPresetPicker {
+	GDCLASS(AnchorPresetPicker, ControlEditorPresetPicker);
+
+	virtual void _preset_button_pressed(const int p_preset) override;
+
+protected:
+	void _notification(int p_notification);
+	static void _bind_methods();
+
+public:
+	AnchorPresetPicker();
+};
+
+class SizeFlagPresetPicker : public ControlEditorPresetPicker {
+	GDCLASS(SizeFlagPresetPicker, ControlEditorPresetPicker);
+
+	CheckButton *expand_button = nullptr;
+
+	bool vertical = false;
+
+	virtual void _preset_button_pressed(const int p_preset) override;
+	void _expand_button_pressed();
+
+protected:
+	void _notification(int p_notification);
+	static void _bind_methods();
+
+public:
+	void set_allowed_flags(Vector<SizeFlags> &p_flags);
+	void set_expand_flag(bool p_expand);
+
+	SizeFlagPresetPicker(bool p_vertical);
+};
+
+class ControlEditorToolbar : public HBoxContainer {
+	GDCLASS(ControlEditorToolbar, HBoxContainer);
+
+	EditorSelection *editor_selection = nullptr;
+
+	ControlEditorPopupButton *anchors_button = nullptr;
+	ControlEditorPopupButton *containers_button = nullptr;
+	Button *anchor_mode_button = nullptr;
+
+	SizeFlagPresetPicker *container_h_picker = nullptr;
+	SizeFlagPresetPicker *container_v_picker = nullptr;
+
+	bool anchors_mode = false;
+
+	void _anchors_preset_selected(int p_preset);
+	void _anchors_to_current_ratio();
+	void _anchor_mode_toggled(bool p_status);
+	void _container_flags_selected(int p_flags, bool p_vertical);
+	void _expand_flag_toggled(bool p_expand, bool p_vertical);
+
+	Vector2 _position_to_anchor(const Control *p_control, Vector2 position);
+	bool _is_node_locked(const Node *p_node);
+	List<Control *> _get_edited_controls();
+	void _selection_changed();
+
+protected:
+	void _notification(int p_notification);
+
+	static ControlEditorToolbar *singleton;
+
+public:
+	bool is_anchors_mode_enabled() { return anchors_mode; }
+
+	static ControlEditorToolbar *get_singleton() { return singleton; }
+
+	ControlEditorToolbar();
+};
+
+// Editor plugin.
+class ControlEditorPlugin : public EditorPlugin {
+	GDCLASS(ControlEditorPlugin, EditorPlugin);
+
+	ControlEditorToolbar *toolbar = nullptr;
+
+public:
+	virtual String get_plugin_name() const override { return "Control"; }
+
+	ControlEditorPlugin();
+};

editor/scene/gui/font_config_plugin.h

@@ -0,0 +1,268 @@
+/**************************************************************************/
+/*  font_config_plugin.h                                                  */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#pragma once
+
+#include "editor/inspector/editor_properties.h"
+#include "editor/inspector/editor_properties_array_dict.h"
+#include "editor/plugins/editor_plugin.h"
+
+/*************************************************************************/
+
+class EditorPropertyFontMetaObject : public RefCounted {
+	GDCLASS(EditorPropertyFontMetaObject, RefCounted);
+
+	Dictionary dict;
+
+protected:
+	bool _set(const StringName &p_name, const Variant &p_value);
+	bool _get(const StringName &p_name, Variant &r_ret) const;
+
+public:
+	void set_dict(const Dictionary &p_dict);
+	Dictionary get_dict();
+};
+
+/*************************************************************************/
+
+class EditorPropertyFontOTObject : public RefCounted {
+	GDCLASS(EditorPropertyFontOTObject, RefCounted);
+
+	Dictionary dict;
+	Dictionary defaults_dict;
+
+protected:
+	bool _set(const StringName &p_name, const Variant &p_value);
+	bool _get(const StringName &p_name, Variant &r_ret) const;
+	bool _property_can_revert(const StringName &p_name) const;
+	bool _property_get_revert(const StringName &p_name, Variant &r_property) const;
+
+public:
+	void set_dict(const Dictionary &p_dict);
+	Dictionary get_dict();
+
+	void set_defaults(const Dictionary &p_dict);
+	Dictionary get_defaults();
+};
+
+/*************************************************************************/
+
+class EditorPropertyFontMetaOverride : public EditorProperty {
+	GDCLASS(EditorPropertyFontMetaOverride, EditorProperty);
+
+	Ref<EditorPropertyFontMetaObject> object;
+
+	MarginContainer *container = nullptr;
+	VBoxContainer *property_vbox = nullptr;
+
+	Button *edit = nullptr;
+	PopupMenu *menu = nullptr;
+	EditorLocaleDialog *locale_select = nullptr;
+
+	Vector<String> script_codes;
+
+	bool script_editor = false;
+	bool updating = false;
+	int page_length = 20;
+	int page_index = 0;
+	EditorPaginator *paginator = nullptr;
+
+protected:
+	void _edit_pressed();
+	void _page_changed(int p_page);
+	void _property_changed(const String &p_property, const Variant &p_value, const String &p_name = "", bool p_changing = false);
+	void _remove(Object *p_button, const String &p_key);
+	void _add_menu();
+	void _add_script(int p_option);
+	void _add_lang(const String &p_locale);
+	void _object_id_selected(const StringName &p_property, ObjectID p_id);
+
+public:
+	virtual void update_property() override;
+
+	EditorPropertyFontMetaOverride(bool p_script);
+};
+
+/*************************************************************************/
+
+class EditorPropertyOTVariation : public EditorProperty {
+	GDCLASS(EditorPropertyOTVariation, EditorProperty);
+
+	Ref<EditorPropertyFontOTObject> object;
+
+	MarginContainer *container = nullptr;
+	VBoxContainer *property_vbox = nullptr;
+
+	Button *edit = nullptr;
+
+	bool updating = false;
+	int page_length = 20;
+	int page_index = 0;
+	EditorPaginator *paginator = nullptr;
+
+protected:
+	static void _bind_methods() {}
+
+	void _edit_pressed();
+	void _page_changed(int p_page);
+	void _property_changed(const String &p_property, const Variant &p_value, const String &p_name = "", bool p_changing = false);
+	void _object_id_selected(const StringName &p_property, ObjectID p_id);
+
+public:
+	virtual void update_property() override;
+
+	EditorPropertyOTVariation();
+};
+
+/*************************************************************************/
+
+class EditorPropertyOTFeatures : public EditorProperty {
+	GDCLASS(EditorPropertyOTFeatures, EditorProperty);
+
+	enum FeatureGroups {
+		FGRP_STYLISTIC_SET,
+		FGRP_CHARACTER_VARIANT,
+		FGRP_CAPITLS,
+		FGRP_LIGATURES,
+		FGRP_ALTERNATES,
+		FGRP_EAL,
+		FGRP_EAW,
+		FGRP_NUMAL,
+		FGRP_CUSTOM,
+		FGRP_MAX,
+	};
+
+	Ref<EditorPropertyFontOTObject> object;
+
+	MarginContainer *container = nullptr;
+	VBoxContainer *property_vbox = nullptr;
+
+	Button *edit = nullptr;
+	PopupMenu *menu = nullptr;
+	PopupMenu *menu_sub[FGRP_MAX];
+	String group_names[FGRP_MAX];
+
+	bool updating = false;
+	int page_length = 20;
+	int page_index = 0;
+	EditorPaginator *paginator = nullptr;
+
+protected:
+	void _edit_pressed();
+	void _page_changed(int p_page);
+	void _property_changed(const String &p_property, const Variant &p_value, const String &p_name = "", bool p_changing = false);
+	void _remove(Object *p_button, int p_key);
+	void _add_menu();
+	void _add_feature(int p_option);
+	void _object_id_selected(const StringName &p_property, ObjectID p_id);
+
+public:
+	virtual void update_property() override;
+
+	EditorPropertyOTFeatures();
+};
+
+/*************************************************************************/
+
+class EditorInspectorPluginFontVariation : public EditorInspectorPlugin {
+	GDCLASS(EditorInspectorPluginFontVariation, EditorInspectorPlugin);
+
+public:
+	virtual bool can_handle(Object *p_object) override;
+	virtual bool parse_property(Object *p_object, const Variant::Type p_type, const String &p_path, const PropertyHint p_hint, const String &p_hint_text, const BitField<PropertyUsageFlags> p_usage, const bool p_wide = false) override;
+};
+
+/*************************************************************************/
+
+class FontPreview : public Control {
+	GDCLASS(FontPreview, Control);
+
+protected:
+	void _notification(int p_what);
+	static void _bind_methods();
+
+	Ref<Font> prev_font;
+
+	void _preview_changed();
+
+public:
+	virtual Size2 get_minimum_size() const override;
+
+	void set_data(const Ref<Font> &p_f);
+};
+
+/*************************************************************************/
+
+class EditorInspectorPluginFontPreview : public EditorInspectorPlugin {
+	GDCLASS(EditorInspectorPluginFontPreview, EditorInspectorPlugin);
+
+public:
+	virtual bool can_handle(Object *p_object) override;
+	virtual void parse_begin(Object *p_object) override;
+	virtual bool parse_property(Object *p_object, const Variant::Type p_type, const String &p_path, const PropertyHint p_hint, const String &p_hint_text, const BitField<PropertyUsageFlags> p_usage, const bool p_wide = false) override;
+};
+
+/*************************************************************************/
+
+class EditorPropertyFontNamesArray : public EditorPropertyArray {
+	GDCLASS(EditorPropertyFontNamesArray, EditorPropertyArray);
+
+	PopupMenu *menu = nullptr;
+
+protected:
+	virtual void _add_element() override;
+
+	void _add_font(int p_option);
+	static void _bind_methods() {}
+
+public:
+	EditorPropertyFontNamesArray();
+};
+
+/*************************************************************************/
+
+class EditorInspectorPluginSystemFont : public EditorInspectorPlugin {
+	GDCLASS(EditorInspectorPluginSystemFont, EditorInspectorPlugin);
+
+public:
+	virtual bool can_handle(Object *p_object) override;
+	virtual bool parse_property(Object *p_object, const Variant::Type p_type, const String &p_path, const PropertyHint p_hint, const String &p_hint_text, const BitField<PropertyUsageFlags> p_usage, const bool p_wide = false) override;
+};
+
+/*************************************************************************/
+
+class FontEditorPlugin : public EditorPlugin {
+	GDCLASS(FontEditorPlugin, EditorPlugin);
+
+public:
+	FontEditorPlugin();
+
+	virtual String get_plugin_name() const override { return "Font"; }
+};

editor/scene/gui/style_box_editor_plugin.cpp

@@ -0,0 +1,138 @@
+/**************************************************************************/
+/*  style_box_editor_plugin.cpp                                           */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#include "style_box_editor_plugin.h"
+
+#include "editor/themes/editor_scale.h"
+#include "scene/gui/button.h"
+#include "scene/resources/style_box_texture.h"
+
+bool StyleBoxPreview::grid_preview_enabled = true;
+
+void StyleBoxPreview::_grid_preview_toggled(bool p_active) {
+	grid_preview_enabled = p_active;
+	queue_redraw();
+}
+
+void StyleBoxPreview::edit(const Ref<StyleBox> &p_stylebox) {
+	if (stylebox.is_valid()) {
+		stylebox->disconnect_changed(callable_mp((CanvasItem *)this, &CanvasItem::queue_redraw));
+	}
+	stylebox = p_stylebox;
+	if (stylebox.is_valid()) {
+		stylebox->connect_changed(callable_mp((CanvasItem *)this, &CanvasItem::queue_redraw));
+	}
+	Ref<StyleBoxTexture> sbt = stylebox;
+	grid_preview->set_visible(sbt.is_valid());
+	queue_redraw();
+}
+
+void StyleBoxPreview::_notification(int p_what) {
+	switch (p_what) {
+		case NOTIFICATION_THEME_CHANGED: {
+			set_texture(get_editor_theme_icon(SNAME("Checkerboard")));
+			grid_preview->set_button_icon(get_editor_theme_icon(SNAME("StyleBoxGrid")));
+		} break;
+		case NOTIFICATION_DRAW: {
+			_redraw();
+		} break;
+	}
+}
+
+void StyleBoxPreview::_redraw() {
+	if (stylebox.is_valid()) {
+		float grid_button_width = get_editor_theme_icon(SNAME("StyleBoxGrid"))->get_size().x;
+		Rect2 preview_rect = get_rect();
+		preview_rect = preview_rect.grow(-grid_button_width);
+
+		// Re-adjust preview panel to fit all drawn content.
+		Rect2 drawing_rect = stylebox->get_draw_rect(preview_rect);
+		preview_rect.size -= drawing_rect.size - preview_rect.size;
+		preview_rect.position -= drawing_rect.position - preview_rect.position;
+
+		draw_style_box(stylebox, preview_rect);
+
+		Ref<StyleBoxTexture> sbt = stylebox;
+		// Draw the "grid". Use white lines, as well as subtle black lines to ensure contrast.
+		if (sbt.is_valid() && grid_preview->is_pressed()) {
+			const Color dark_color = Color(0, 0, 0, 0.4);
+			const Color bright_color = Color(1, 1, 1, 0.8);
+			int x_left = drawing_rect.position.x + sbt->get_margin(SIDE_LEFT);
+			int x_right = drawing_rect.position.x + drawing_rect.size.width - sbt->get_margin(SIDE_RIGHT);
+			int y_top = drawing_rect.position.y + sbt->get_margin(SIDE_TOP);
+			int y_bottom = drawing_rect.position.y + drawing_rect.size.height - sbt->get_margin(SIDE_BOTTOM);
+
+			draw_line(Point2(x_left + 2, 0), Point2(x_left + 2, get_size().height), dark_color);
+			draw_line(Point2(x_right + 1, 0), Point2(x_right + 1, get_size().height), dark_color);
+			draw_line(Point2(0, y_top + 2), Point2(get_size().width, y_top + 2), dark_color);
+			draw_line(Point2(0, y_bottom + 1), Point2(get_size().width, y_bottom + 1), dark_color);
+
+			draw_line(Point2(x_left + 1, 0), Point2(x_left + 1, get_size().height), bright_color);
+			draw_line(Point2(x_right, 0), Point2(x_right, get_size().height), bright_color);
+			draw_line(Point2(0, y_top + 1), Point2(get_size().width, y_top + 1), bright_color);
+			draw_line(Point2(0, y_bottom), Point2(get_size().width, y_bottom), bright_color);
+		}
+	}
+}
+
+StyleBoxPreview::StyleBoxPreview() {
+	set_clip_contents(true);
+	set_custom_minimum_size(Size2(0, 150) * EDSCALE);
+	set_stretch_mode(TextureRect::STRETCH_TILE);
+	set_texture_repeat(CanvasItem::TEXTURE_REPEAT_ENABLED);
+	set_anchors_and_offsets_preset(PRESET_FULL_RECT);
+
+	grid_preview = memnew(Button);
+	// This theme variation works better than the normal theme because there's no focus highlight.
+	grid_preview->set_theme_type_variation("PreviewLightButton");
+	grid_preview->set_tooltip_text(TTRC("Toggle margins preview grid."));
+	grid_preview->set_toggle_mode(true);
+	grid_preview->connect(SceneStringName(toggled), callable_mp(this, &StyleBoxPreview::_grid_preview_toggled));
+	grid_preview->set_pressed(grid_preview_enabled);
+	add_child(grid_preview);
+}
+
+bool EditorInspectorPluginStyleBox::can_handle(Object *p_object) {
+	return Object::cast_to<StyleBox>(p_object) != nullptr;
+}
+
+void EditorInspectorPluginStyleBox::parse_begin(Object *p_object) {
+	Ref<StyleBox> sb = Ref<StyleBox>(Object::cast_to<StyleBox>(p_object));
+
+	StyleBoxPreview *preview = memnew(StyleBoxPreview);
+	preview->edit(sb);
+	add_custom_control(preview);
+}
+
+StyleBoxEditorPlugin::StyleBoxEditorPlugin() {
+	Ref<EditorInspectorPluginStyleBox> inspector_plugin;
+	inspector_plugin.instantiate();
+	add_inspector_plugin(inspector_plugin);
+}

editor/scene/gui/style_box_editor_plugin.h

@@ -0,0 +1,75 @@
+/**************************************************************************/
+/*  style_box_editor_plugin.h                                             */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#pragma once
+
+#include "editor/inspector/editor_inspector.h"
+#include "editor/plugins/editor_plugin.h"
+#include "scene/gui/texture_rect.h"
+
+class Button;
+class StyleBox;
+
+class StyleBoxPreview : public TextureRect {
+	GDCLASS(StyleBoxPreview, TextureRect);
+
+	Button *grid_preview = nullptr;
+	Ref<StyleBox> stylebox;
+
+	void _sb_changed();
+	void _redraw();
+	static bool grid_preview_enabled;
+	void _grid_preview_toggled(bool p_active);
+
+protected:
+	void _notification(int p_what);
+
+public:
+	void edit(const Ref<StyleBox> &p_stylebox);
+
+	StyleBoxPreview();
+};
+
+class EditorInspectorPluginStyleBox : public EditorInspectorPlugin {
+	GDCLASS(EditorInspectorPluginStyleBox, EditorInspectorPlugin);
+
+public:
+	virtual bool can_handle(Object *p_object) override;
+	virtual void parse_begin(Object *p_object) override;
+};
+
+class StyleBoxEditorPlugin : public EditorPlugin {
+	GDCLASS(StyleBoxEditorPlugin, EditorPlugin);
+
+public:
+	virtual String get_plugin_name() const override { return "StyleBox"; }
+
+	StyleBoxEditorPlugin();
+};

editor/scene/gui/theme_editor_plugin.h

@@ -0,0 +1,498 @@
+/**************************************************************************/
+/*  theme_editor_plugin.h                                                 */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#pragma once
+
+#include "editor/plugins/editor_plugin.h"
+#include "editor/scene/gui/theme_editor_preview.h"
+#include "scene/gui/dialogs.h"
+#include "scene/gui/margin_container.h"
+#include "scene/gui/tree.h"
+#include "scene/resources/theme.h"
+
+class Button;
+class CheckButton;
+class EditorFileDialog;
+class ItemList;
+class Label;
+class LineEdit;
+class OptionButton;
+class PanelContainer;
+class TabBar;
+class TabContainer;
+class ThemeEditorPlugin;
+class TextureRect;
+
+class ThemeItemImportTree : public VBoxContainer {
+	GDCLASS(ThemeItemImportTree, VBoxContainer);
+
+	Ref<Theme> edited_theme;
+	Ref<Theme> base_theme;
+
+	struct ThemeItem {
+		String type_name;
+		Theme::DataType data_type;
+		String item_name;
+
+		bool operator<(const ThemeItem &p_item) const {
+			if (type_name == p_item.type_name && data_type == p_item.data_type) {
+				return item_name < p_item.item_name;
+			}
+			if (type_name == p_item.type_name) {
+				return data_type < p_item.data_type;
+			}
+			return type_name < p_item.type_name;
+		}
+	};
+
+	enum ItemCheckedState {
+		SELECT_IMPORT_DEFINITION,
+		SELECT_IMPORT_FULL,
+	};
+
+	RBMap<ThemeItem, ItemCheckedState> selected_items;
+
+	LineEdit *import_items_filter = nullptr;
+
+	Tree *import_items_tree = nullptr;
+	List<TreeItem *> tree_color_items;
+	List<TreeItem *> tree_constant_items;
+	List<TreeItem *> tree_font_items;
+	List<TreeItem *> tree_font_size_items;
+	List<TreeItem *> tree_icon_items;
+	List<TreeItem *> tree_stylebox_items;
+
+	bool updating_tree = false;
+
+	enum ItemActionFlag {
+		IMPORT_ITEM = 1,
+		IMPORT_ITEM_DATA = 2,
+	};
+
+	TextureRect *select_colors_icon = nullptr;
+	Label *select_colors_label = nullptr;
+	Button *select_all_colors_button = nullptr;
+	Button *select_full_colors_button = nullptr;
+	Button *deselect_all_colors_button = nullptr;
+	Label *total_selected_colors_label = nullptr;
+
+	TextureRect *select_constants_icon = nullptr;
+	Label *select_constants_label = nullptr;
+	Button *select_all_constants_button = nullptr;
+	Button *select_full_constants_button = nullptr;
+	Button *deselect_all_constants_button = nullptr;
+	Label *total_selected_constants_label = nullptr;
+
+	TextureRect *select_fonts_icon = nullptr;
+	Label *select_fonts_label = nullptr;
+	Button *select_all_fonts_button = nullptr;
+	Button *select_full_fonts_button = nullptr;
+	Button *deselect_all_fonts_button = nullptr;
+	Label *total_selected_fonts_label = nullptr;
+
+	TextureRect *select_font_sizes_icon = nullptr;
+	Label *select_font_sizes_label = nullptr;
+	Button *select_all_font_sizes_button = nullptr;
+	Button *select_full_font_sizes_button = nullptr;
+	Button *deselect_all_font_sizes_button = nullptr;
+	Label *total_selected_font_sizes_label = nullptr;
+
+	TextureRect *select_icons_icon = nullptr;
+	Label *select_icons_label = nullptr;
+	Button *select_all_icons_button = nullptr;
+	Button *select_full_icons_button = nullptr;
+	Button *deselect_all_icons_button = nullptr;
+	Label *total_selected_icons_label = nullptr;
+
+	TextureRect *select_styleboxes_icon = nullptr;
+	Label *select_styleboxes_label = nullptr;
+	Button *select_all_styleboxes_button = nullptr;
+	Button *select_full_styleboxes_button = nullptr;
+	Button *deselect_all_styleboxes_button = nullptr;
+	Label *total_selected_styleboxes_label = nullptr;
+
+	HBoxContainer *select_icons_warning_hb = nullptr;
+	TextureRect *select_icons_warning_icon = nullptr;
+	Label *select_icons_warning = nullptr;
+
+	Button *import_collapse_types_button = nullptr;
+	Button *import_expand_types_button = nullptr;
+	Button *import_select_all_button = nullptr;
+	Button *import_select_full_button = nullptr;
+	Button *import_deselect_all_button = nullptr;
+
+	void _update_items_tree();
+	void _toggle_type_items(bool p_collapse);
+	void _filter_text_changed(const String &p_value);
+
+	void _store_selected_item(TreeItem *p_tree_item);
+	void _restore_selected_item(TreeItem *p_tree_item);
+	void _update_total_selected(Theme::DataType p_data_type);
+
+	void _tree_item_edited();
+	void _check_propagated_to_tree_item(Object *p_obj, int p_column);
+	void _select_all_subitems(TreeItem *p_root_item, bool p_select_with_data);
+	void _deselect_all_subitems(TreeItem *p_root_item, bool p_deselect_completely);
+
+	void _select_all_items_pressed();
+	void _select_full_items_pressed();
+	void _deselect_all_items_pressed();
+
+	void _select_all_data_type_pressed(int p_data_type);
+	void _select_full_data_type_pressed(int p_data_type);
+	void _deselect_all_data_type_pressed(int p_data_type);
+
+	void _import_selected();
+
+protected:
+	void _notification(int p_what);
+	static void _bind_methods();
+
+public:
+	void set_edited_theme(const Ref<Theme> &p_theme);
+	void set_base_theme(const Ref<Theme> &p_theme);
+	void reset_item_tree();
+
+	bool has_selected_items() const;
+
+	ThemeItemImportTree();
+};
+
+class ThemeTypeEditor;
+
+class ThemeItemEditorDialog : public AcceptDialog {
+	GDCLASS(ThemeItemEditorDialog, AcceptDialog);
+
+	ThemeTypeEditor *theme_type_editor = nullptr;
+
+	Ref<Theme> edited_theme;
+
+	TabContainer *tc = nullptr;
+
+	enum TypesTreeAction {
+		TYPES_TREE_REMOVE_ITEM,
+	};
+
+	Tree *edit_type_list = nullptr;
+	LineEdit *edit_add_type_value = nullptr;
+	Button *edit_add_type_button = nullptr;
+	String edited_item_type;
+
+	Button *edit_items_add_color = nullptr;
+	Button *edit_items_add_constant = nullptr;
+	Button *edit_items_add_font = nullptr;
+	Button *edit_items_add_font_size = nullptr;
+	Button *edit_items_add_icon = nullptr;
+	Button *edit_items_add_stylebox = nullptr;
+	Button *edit_items_remove_class = nullptr;
+	Button *edit_items_remove_custom = nullptr;
+	Button *edit_items_remove_all = nullptr;
+	Tree *edit_items_tree = nullptr;
+	Label *edit_items_message = nullptr;
+
+	enum ItemsTreeAction {
+		ITEMS_TREE_RENAME_ITEM,
+		ITEMS_TREE_REMOVE_ITEM,
+		ITEMS_TREE_REMOVE_DATA_TYPE,
+	};
+
+	ConfirmationDialog *edit_theme_item_dialog = nullptr;
+	VBoxContainer *edit_theme_item_old_vb = nullptr;
+	Label *theme_item_old_name = nullptr;
+	LineEdit *theme_item_name = nullptr;
+
+	enum ItemPopupMode {
+		CREATE_THEME_ITEM,
+		RENAME_THEME_ITEM,
+		ITEM_POPUP_MODE_MAX
+	};
+
+	ItemPopupMode item_popup_mode = ITEM_POPUP_MODE_MAX;
+	String edit_item_old_name;
+	Theme::DataType edit_item_data_type = Theme::DATA_TYPE_MAX;
+
+	ThemeItemImportTree *import_default_theme_items = nullptr;
+	ThemeItemImportTree *import_editor_theme_items = nullptr;
+	ThemeItemImportTree *import_other_theme_items = nullptr;
+
+	LineEdit *import_another_theme_value = nullptr;
+	Button *import_another_theme_button = nullptr;
+	EditorFileDialog *import_another_theme_dialog = nullptr;
+
+	ConfirmationDialog *confirm_closing_dialog = nullptr;
+
+	void ok_pressed() override;
+	void _close_dialog();
+
+	void _dialog_about_to_show();
+	void _update_edit_types();
+	void _edited_type_selected();
+	void _edited_type_edited();
+	void _edited_type_button_pressed(Object *p_item, int p_column, int p_id, MouseButton p_button);
+
+	void _update_edit_item_tree(String p_item_type);
+	void _item_tree_button_pressed(Object *p_item, int p_column, int p_id, MouseButton p_button);
+
+	void _add_theme_type();
+	void _add_theme_item(Theme::DataType p_data_type, const String &p_item_name, const String &p_item_type);
+	void _remove_theme_type(const String &p_theme_type);
+	void _remove_data_type_items(Theme::DataType p_data_type, String p_item_type);
+	void _remove_class_items();
+	void _remove_custom_items();
+	void _remove_all_items();
+
+	void _open_add_theme_item_dialog(int p_data_type);
+	void _open_rename_theme_item_dialog(Theme::DataType p_data_type, String p_item_name);
+	void _confirm_edit_theme_item();
+	void _edit_theme_item_gui_input(const Ref<InputEvent> &p_event);
+
+	void _open_select_another_theme();
+	void _select_another_theme_cbk(const String &p_path);
+
+protected:
+	void _notification(int p_what);
+	static void _bind_methods();
+
+public:
+	void set_edited_theme(const Ref<Theme> &p_theme);
+
+	ThemeItemEditorDialog(ThemeTypeEditor *p_theme_editor);
+};
+
+class ThemeTypeDialog : public ConfirmationDialog {
+	GDCLASS(ThemeTypeDialog, ConfirmationDialog);
+
+	Ref<Theme> edited_theme;
+	bool include_own_types = false;
+
+	String pre_submitted_value;
+
+	LineEdit *add_type_filter = nullptr;
+	ItemList *add_type_options = nullptr;
+	ConfirmationDialog *add_type_confirmation = nullptr;
+
+	void _dialog_about_to_show();
+	void ok_pressed() override;
+
+	void _update_add_type_options(const String &p_filter = "");
+
+	void _add_type_filter_cbk(const String &p_value);
+	void _type_filter_input(const Ref<InputEvent> &p_event);
+	void _add_type_options_cbk(int p_index);
+	void _add_type_dialog_entered(const String &p_value);
+	void _add_type_dialog_activated(int p_index);
+
+	void _add_type_selected(const String &p_type_name);
+	void _add_type_confirmed();
+
+protected:
+	void _notification(int p_what);
+	static void _bind_methods();
+
+public:
+	void set_edited_theme(const Ref<Theme> &p_theme);
+	void set_include_own_types(bool p_enable);
+
+	ThemeTypeDialog();
+};
+
+// Custom `Label` needed to use `EditorHelpBit` to display theme item documentation.
+class ThemeItemLabel : public Label {
+	virtual Control *make_custom_tooltip(const String &p_text) const;
+};
+
+class ThemeTypeEditor : public MarginContainer {
+	GDCLASS(ThemeTypeEditor, MarginContainer);
+
+	Ref<Theme> edited_theme;
+	String edited_type;
+	bool updating = false;
+
+	struct LeadingStylebox {
+		bool pinned = false;
+		StringName item_name;
+		Ref<StyleBox> stylebox;
+		Ref<StyleBox> ref_stylebox;
+	};
+
+	LeadingStylebox leading_stylebox;
+
+	OptionButton *theme_type_list = nullptr;
+	Button *add_type_button = nullptr;
+	Button *rename_type_button = nullptr;
+	ConfirmationDialog *theme_type_rename_dialog = nullptr;
+	LineEdit *theme_type_rename_line_edit = nullptr;
+	Button *remove_type_button = nullptr;
+
+	CheckButton *show_default_items_button = nullptr;
+
+	TabContainer *data_type_tabs = nullptr;
+	VBoxContainer *color_items_list = nullptr;
+	VBoxContainer *constant_items_list = nullptr;
+	VBoxContainer *font_items_list = nullptr;
+	VBoxContainer *font_size_items_list = nullptr;
+	VBoxContainer *icon_items_list = nullptr;
+	VBoxContainer *stylebox_items_list = nullptr;
+
+	LineEdit *type_variation_edit = nullptr;
+	Button *type_variation_button = nullptr;
+	Label *type_variation_locked = nullptr;
+
+	enum TypeDialogMode {
+		ADD_THEME_TYPE,
+		ADD_VARIATION_BASE,
+	};
+
+	TypeDialogMode add_type_mode = ADD_THEME_TYPE;
+	ThemeTypeDialog *add_type_dialog = nullptr;
+
+	Vector<Control *> focusables;
+	Timer *update_debounce_timer = nullptr;
+
+	VBoxContainer *_create_item_list(Theme::DataType p_data_type);
+	void _update_type_list();
+	void _update_type_list_debounced();
+	HashMap<StringName, bool> _get_type_items(String p_type_name, Theme::DataType p_type, bool p_include_default);
+	HBoxContainer *_create_property_control(Theme::DataType p_data_type, String p_item_name, bool p_editable);
+	void _add_focusable(Control *p_control);
+	void _update_type_items();
+
+	void _list_type_selected(int p_index);
+	void _add_type_button_cbk();
+	void _rename_type_button_cbk();
+	void _theme_type_rename_dialog_confirmed();
+	void _remove_type_button_cbk();
+	void _add_default_type_items();
+
+	void _update_add_button(const String &p_text, LineEdit *p_for_edit);
+	void _item_add_cbk(int p_data_type, Control *p_control);
+	void _item_add_lineedit_cbk(String p_value, int p_data_type, Control *p_control);
+	void _item_override_cbk(int p_data_type, String p_item_name);
+	void _item_remove_cbk(int p_data_type, String p_item_name);
+	void _item_rename_cbk(int p_data_type, String p_item_name, Control *p_control);
+	void _item_rename_confirmed(int p_data_type, String p_item_name, Control *p_control);
+	void _item_rename_entered(String p_value, int p_data_type, String p_item_name, Control *p_control);
+	void _item_rename_canceled(int p_data_type, String p_item_name, Control *p_control);
+
+	void _color_item_changed(Color p_value, String p_item_name);
+	void _constant_item_changed(float p_value, String p_item_name);
+	void _font_size_item_changed(float p_value, String p_item_name);
+	void _edit_resource_item(Ref<Resource> p_resource, bool p_edit);
+	void _font_item_changed(Ref<Font> p_value, String p_item_name);
+	void _icon_item_changed(Ref<Texture2D> p_value, String p_item_name);
+	void _stylebox_item_changed(Ref<StyleBox> p_value, String p_item_name);
+	void _change_pinned_stylebox();
+	void _on_pin_leader_button_pressed(Control *p_editor, String p_item_name);
+	void _pin_leading_stylebox(String p_item_name, Ref<StyleBox> p_stylebox);
+	void _on_unpin_leader_button_pressed();
+	void _unpin_leading_stylebox();
+	void _update_stylebox_from_leading();
+
+	void _type_variation_changed(const String p_value);
+	void _add_type_variation_cbk();
+
+	void _add_type_dialog_selected(const String p_type_name);
+
+protected:
+	void _notification(int p_what);
+	static void _bind_methods();
+
+public:
+	void set_edited_theme(const Ref<Theme> &p_theme);
+	void select_type(String p_type_name);
+	bool is_stylebox_pinned(Ref<StyleBox> p_stylebox);
+
+	ThemeTypeEditor();
+};
+
+class ThemeEditor : public VBoxContainer {
+	GDCLASS(ThemeEditor, VBoxContainer);
+
+	friend class ThemeEditorPlugin;
+	ThemeEditorPlugin *plugin = nullptr;
+
+	Ref<Theme> theme;
+
+	TabBar *preview_tabs = nullptr;
+	PanelContainer *preview_tabs_content = nullptr;
+	Button *add_preview_button = nullptr;
+	EditorFileDialog *preview_scene_dialog = nullptr;
+
+	ThemeTypeEditor *theme_type_editor = nullptr;
+
+	Label *theme_name = nullptr;
+	ThemeItemEditorDialog *theme_edit_dialog = nullptr;
+
+	void _theme_save_button_cbk(bool p_save_as);
+	void _theme_edit_button_cbk();
+	void _theme_close_button_cbk();
+	void _scene_closed(const String &p_path);
+	void _resource_saved(const Ref<Resource> &p_resource);
+	void _files_moved(const String &p_old_path, const String &p_new_path);
+	void _update_theme_name(const String &p_name);
+
+	void _add_preview_button_cbk();
+	void _preview_scene_dialog_cbk(const String &p_path);
+	void _add_preview_tab(ThemeEditorPreview *p_preview_tab, const String &p_preview_name, const Ref<Texture2D> &p_icon);
+	void _change_preview_tab(int p_tab);
+	void _remove_preview_tab(int p_tab);
+	void _remove_preview_tab_invalid(Node *p_tab_control);
+	void _update_preview_tab(Node *p_tab_control);
+	void _preview_control_picked(String p_class_name);
+
+protected:
+	void _notification(int p_what);
+
+public:
+	void edit(const Ref<Theme> &p_theme);
+	Ref<Theme> get_edited_theme();
+
+	bool can_drop_data_fw(const Point2 &p_point, const Variant &p_data, Control *p_from);
+	void drop_data_fw(const Point2 &p_point, const Variant &p_data, Control *p_from);
+
+	ThemeEditor();
+};
+
+class ThemeEditorPlugin : public EditorPlugin {
+	GDCLASS(ThemeEditorPlugin, EditorPlugin);
+
+	ThemeEditor *theme_editor = nullptr;
+	Button *button = nullptr;
+
+public:
+	virtual String get_plugin_name() const override { return "Theme"; }
+	bool has_main_screen() const override { return false; }
+	virtual void edit(Object *p_object) override;
+	virtual bool handles(Object *p_object) const override;
+	virtual void make_visible(bool p_visible) override;
+	virtual bool can_auto_hide() const override;
+
+	ThemeEditorPlugin();
+};

editor/scene/gui/theme_editor_preview.cpp

@@ -0,0 +1,545 @@
+/**************************************************************************/
+/*  theme_editor_preview.cpp                                              */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#include "theme_editor_preview.h"
+
+#include "core/config/project_settings.h"
+#include "editor/editor_node.h"
+#include "editor/editor_string_names.h"
+#include "editor/themes/editor_scale.h"
+#include "scene/gui/button.h"
+#include "scene/gui/check_box.h"
+#include "scene/gui/check_button.h"
+#include "scene/gui/color_picker.h"
+#include "scene/gui/color_rect.h"
+#include "scene/gui/label.h"
+#include "scene/gui/margin_container.h"
+#include "scene/gui/menu_button.h"
+#include "scene/gui/option_button.h"
+#include "scene/gui/panel.h"
+#include "scene/gui/progress_bar.h"
+#include "scene/gui/scroll_container.h"
+#include "scene/gui/separator.h"
+#include "scene/gui/slider.h"
+#include "scene/gui/spin_box.h"
+#include "scene/gui/tab_container.h"
+#include "scene/gui/text_edit.h"
+#include "scene/gui/tree.h"
+#include "scene/resources/packed_scene.h"
+#include "scene/theme/theme_db.h"
+
+constexpr double REFRESH_TIMER = 1.5;
+
+void ThemeEditorPreview::set_preview_theme(const Ref<Theme> &p_theme) {
+	preview_content->set_theme(p_theme);
+}
+
+void ThemeEditorPreview::add_preview_overlay(Control *p_overlay) {
+	preview_overlay->add_child(p_overlay);
+	p_overlay->hide();
+}
+
+void ThemeEditorPreview::_propagate_redraw(Control *p_at) {
+	p_at->notification(NOTIFICATION_THEME_CHANGED);
+	p_at->update_minimum_size();
+	p_at->queue_redraw();
+	for (int i = 0; i < p_at->get_child_count(); i++) {
+		Control *a = Object::cast_to<Control>(p_at->get_child(i));
+		if (a) {
+			_propagate_redraw(a);
+		}
+	}
+}
+
+void ThemeEditorPreview::_refresh_interval() {
+	// In case the project settings have changed.
+	preview_bg->set_color(GLOBAL_GET("rendering/environment/defaults/default_clear_color"));
+
+	_propagate_redraw(preview_bg);
+	_propagate_redraw(preview_content);
+}
+
+void ThemeEditorPreview::_preview_visibility_changed() {
+	set_process(is_visible_in_tree());
+}
+
+void ThemeEditorPreview::_picker_button_cbk() {
+	picker_overlay->set_visible(picker_button->is_pressed());
+	if (picker_button->is_pressed()) {
+		_reset_picker_overlay();
+	}
+}
+
+Control *ThemeEditorPreview::_find_hovered_control(Control *p_parent, Vector2 p_mouse_position) {
+	Control *found = nullptr;
+
+	for (int i = p_parent->get_child_count() - 1; i >= 0; i--) {
+		Control *cc = Object::cast_to<Control>(p_parent->get_child(i));
+		if (!cc || !cc->is_visible()) {
+			continue;
+		}
+
+		Rect2 crect = cc->get_rect();
+		if (crect.has_point(p_mouse_position)) {
+			// Check if there is a child control under mouse.
+			if (cc->get_child_count() > 0) {
+				found = _find_hovered_control(cc, p_mouse_position - cc->get_position());
+			}
+
+			// If there are no applicable children, use the control itself.
+			if (!found) {
+				found = cc;
+			}
+			break;
+		}
+	}
+
+	return found;
+}
+
+void ThemeEditorPreview::_draw_picker_overlay() {
+	if (!picker_button->is_pressed()) {
+		return;
+	}
+
+	picker_overlay->draw_rect(Rect2(Vector2(0.0, 0.0), picker_overlay->get_size()), theme_cache.preview_picker_overlay_color);
+	if (hovered_control) {
+		Rect2 highlight_rect = hovered_control->get_global_rect();
+		highlight_rect.position = picker_overlay->get_global_transform().affine_inverse().xform(highlight_rect.position);
+		picker_overlay->draw_style_box(theme_cache.preview_picker_overlay, highlight_rect);
+
+		String highlight_name = hovered_control->get_theme_type_variation();
+		if (highlight_name == StringName()) {
+			highlight_name = hovered_control->get_class_name();
+		}
+
+		Rect2 highlight_label_rect = highlight_rect;
+		highlight_label_rect.size = theme_cache.preview_picker_font->get_string_size(highlight_name, HORIZONTAL_ALIGNMENT_LEFT, -1, theme_cache.font_size);
+
+		int margin_top = theme_cache.preview_picker_label->get_margin(SIDE_TOP);
+		int margin_left = theme_cache.preview_picker_label->get_margin(SIDE_LEFT);
+		int margin_bottom = theme_cache.preview_picker_label->get_margin(SIDE_BOTTOM);
+		int margin_right = theme_cache.preview_picker_label->get_margin(SIDE_RIGHT);
+		highlight_label_rect.size.x += margin_left + margin_right;
+		highlight_label_rect.size.y += margin_top + margin_bottom;
+
+		highlight_label_rect.position = highlight_label_rect.position.clamp(Vector2(), picker_overlay->get_size());
+
+		picker_overlay->draw_style_box(theme_cache.preview_picker_label, highlight_label_rect);
+
+		Point2 label_pos = highlight_label_rect.position;
+		label_pos.y += highlight_label_rect.size.y - margin_bottom;
+		label_pos.x += margin_left;
+		picker_overlay->draw_string(theme_cache.preview_picker_font, label_pos, highlight_name, HORIZONTAL_ALIGNMENT_LEFT, -1, theme_cache.font_size);
+	}
+}
+
+void ThemeEditorPreview::_gui_input_picker_overlay(const Ref<InputEvent> &p_event) {
+	if (!picker_button->is_pressed()) {
+		return;
+	}
+
+	Ref<InputEventMouseButton> mb = p_event;
+
+	if (mb.is_valid() && mb->is_pressed() && mb->get_button_index() == MouseButton::LEFT) {
+		if (hovered_control) {
+			StringName theme_type = hovered_control->get_theme_type_variation();
+			if (theme_type == StringName()) {
+				theme_type = hovered_control->get_class_name();
+			}
+
+			emit_signal(SNAME("control_picked"), theme_type);
+			picker_button->set_pressed(false);
+			picker_overlay->set_visible(false);
+			return;
+		}
+	}
+
+	Ref<InputEventMouseMotion> mm = p_event;
+
+	if (mm.is_valid()) {
+		Vector2 mp = preview_content->get_local_mouse_position();
+		hovered_control = _find_hovered_control(preview_content, mp);
+		picker_overlay->queue_redraw();
+	}
+
+	// Forward input to the scroll container underneath to allow scrolling.
+	preview_container->gui_input(p_event);
+}
+
+void ThemeEditorPreview::_reset_picker_overlay() {
+	hovered_control = nullptr;
+	picker_overlay->queue_redraw();
+}
+
+void ThemeEditorPreview::_notification(int p_what) {
+	switch (p_what) {
+		case NOTIFICATION_ENTER_TREE: {
+			if (is_visible_in_tree()) {
+				set_process(true);
+			}
+
+			connect(SceneStringName(visibility_changed), callable_mp(this, &ThemeEditorPreview::_preview_visibility_changed));
+		} break;
+
+		case NOTIFICATION_READY: {
+			Vector<Ref<Theme>> preview_themes;
+			preview_themes.push_back(ThemeDB::get_singleton()->get_default_theme());
+			ThemeDB::get_singleton()->create_theme_context(preview_root, preview_themes);
+		} break;
+
+		case NOTIFICATION_THEME_CHANGED: {
+			picker_button->set_button_icon(get_editor_theme_icon(SNAME("ColorPick")));
+
+			theme_cache.preview_picker_overlay = get_theme_stylebox(SNAME("preview_picker_overlay"), SNAME("ThemeEditor"));
+			theme_cache.preview_picker_overlay_color = get_theme_color(SNAME("preview_picker_overlay_color"), SNAME("ThemeEditor"));
+			theme_cache.preview_picker_label = get_theme_stylebox(SNAME("preview_picker_label"), SNAME("ThemeEditor"));
+			theme_cache.preview_picker_font = get_theme_font(SNAME("status_source"), EditorStringName(EditorFonts));
+			theme_cache.font_size = get_theme_default_font_size();
+		} break;
+
+		case NOTIFICATION_PROCESS: {
+			time_left -= get_process_delta_time();
+			if (time_left < 0) {
+				time_left = REFRESH_TIMER;
+				_refresh_interval();
+			}
+		} break;
+	}
+}
+
+void ThemeEditorPreview::_bind_methods() {
+	ADD_SIGNAL(MethodInfo("control_picked", PropertyInfo(Variant::STRING, "class_name")));
+}
+
+ThemeEditorPreview::ThemeEditorPreview() {
+	preview_toolbar = memnew(HBoxContainer);
+	add_child(preview_toolbar);
+
+	picker_button = memnew(Button);
+	preview_toolbar->add_child(picker_button);
+	picker_button->set_theme_type_variation(SceneStringName(FlatButton));
+	picker_button->set_toggle_mode(true);
+	picker_button->set_tooltip_text(TTR("Toggle the control picker, allowing to visually select control types for edit."));
+	picker_button->connect(SceneStringName(pressed), callable_mp(this, &ThemeEditorPreview::_picker_button_cbk));
+
+	MarginContainer *preview_body = memnew(MarginContainer);
+	preview_body->set_custom_minimum_size(Size2(200, 0) * EDSCALE);
+	preview_body->set_v_size_flags(SIZE_EXPAND_FILL);
+	add_child(preview_body);
+
+	preview_container = memnew(ScrollContainer);
+	preview_body->add_child(preview_container);
+
+	preview_root = memnew(MarginContainer);
+	preview_container->add_child(preview_root);
+	preview_root->set_clip_contents(true);
+	preview_root->set_custom_minimum_size(Size2(450, 0) * EDSCALE);
+	preview_root->set_v_size_flags(SIZE_EXPAND_FILL);
+	preview_root->set_h_size_flags(SIZE_EXPAND_FILL);
+
+	preview_bg = memnew(ColorRect);
+	preview_bg->set_anchors_and_offsets_preset(PRESET_FULL_RECT);
+	preview_bg->set_color(GLOBAL_GET("rendering/environment/defaults/default_clear_color"));
+	preview_root->add_child(preview_bg);
+
+	preview_content = memnew(MarginContainer);
+	preview_content->add_theme_constant_override("margin_right", 4 * EDSCALE);
+	preview_content->add_theme_constant_override("margin_top", 4 * EDSCALE);
+	preview_content->add_theme_constant_override("margin_left", 4 * EDSCALE);
+	preview_content->add_theme_constant_override("margin_bottom", 4 * EDSCALE);
+	preview_root->add_child(preview_content);
+
+	preview_overlay = memnew(MarginContainer);
+	preview_overlay->set_mouse_filter(MOUSE_FILTER_IGNORE);
+	preview_overlay->set_clip_contents(true);
+	preview_body->add_child(preview_overlay);
+
+	picker_overlay = memnew(Control);
+	add_preview_overlay(picker_overlay);
+	picker_overlay->connect(SceneStringName(draw), callable_mp(this, &ThemeEditorPreview::_draw_picker_overlay));
+	picker_overlay->connect(SceneStringName(gui_input), callable_mp(this, &ThemeEditorPreview::_gui_input_picker_overlay));
+	picker_overlay->connect(SceneStringName(mouse_exited), callable_mp(this, &ThemeEditorPreview::_reset_picker_overlay));
+}
+
+void DefaultThemeEditorPreview::_notification(int p_what) {
+	switch (p_what) {
+		case NOTIFICATION_THEME_CHANGED: {
+			test_color_picker_button->set_custom_minimum_size(Size2(0, get_theme_constant(SNAME("color_picker_button_height"), EditorStringName(Editor))));
+		} break;
+	}
+}
+
+DefaultThemeEditorPreview::DefaultThemeEditorPreview() {
+	Panel *main_panel = memnew(Panel);
+	preview_content->add_child(main_panel);
+
+	MarginContainer *main_mc = memnew(MarginContainer);
+	main_mc->add_theme_constant_override("margin_right", 4 * EDSCALE);
+	main_mc->add_theme_constant_override("margin_top", 4 * EDSCALE);
+	main_mc->add_theme_constant_override("margin_left", 4 * EDSCALE);
+	main_mc->add_theme_constant_override("margin_bottom", 4 * EDSCALE);
+	preview_content->add_child(main_mc);
+
+	HBoxContainer *main_hb = memnew(HBoxContainer);
+	main_mc->add_child(main_hb);
+	main_hb->add_theme_constant_override("separation", 20 * EDSCALE);
+
+	VBoxContainer *first_vb = memnew(VBoxContainer);
+	main_hb->add_child(first_vb);
+	first_vb->set_h_size_flags(SIZE_EXPAND_FILL);
+	first_vb->add_theme_constant_override("separation", 10 * EDSCALE);
+
+	first_vb->add_child(memnew(Label("Label")));
+
+	first_vb->add_child(memnew(Button("Button")));
+	Button *bt = memnew(Button);
+	bt->set_text(TTR("Toggle Button"));
+	bt->set_toggle_mode(true);
+	bt->set_pressed(true);
+	first_vb->add_child(bt);
+	bt = memnew(Button);
+	bt->set_text(TTR("Disabled Button"));
+	bt->set_disabled(true);
+	first_vb->add_child(bt);
+	Button *tb = memnew(Button);
+	tb->set_flat(true);
+	tb->set_text("Flat Button");
+	first_vb->add_child(tb);
+
+	CheckButton *cb = memnew(CheckButton);
+	cb->set_text("CheckButton");
+	first_vb->add_child(cb);
+	CheckBox *cbx = memnew(CheckBox);
+	cbx->set_text("CheckBox");
+	first_vb->add_child(cbx);
+
+	MenuButton *test_menu_button = memnew(MenuButton);
+	test_menu_button->set_text("MenuButton");
+	test_menu_button->get_popup()->add_item(TTR("Item"));
+	test_menu_button->get_popup()->add_item(TTR("Disabled Item"));
+	test_menu_button->get_popup()->set_item_disabled(1, true);
+	test_menu_button->get_popup()->add_separator();
+	test_menu_button->get_popup()->add_check_item(TTR("Check Item"));
+	test_menu_button->get_popup()->add_check_item(TTR("Checked Item"));
+	test_menu_button->get_popup()->set_item_checked(4, true);
+	test_menu_button->get_popup()->add_separator();
+	test_menu_button->get_popup()->add_radio_check_item(TTR("Radio Item"));
+	test_menu_button->get_popup()->add_radio_check_item(TTR("Checked Radio Item"));
+	test_menu_button->get_popup()->set_item_checked(7, true);
+	test_menu_button->get_popup()->add_separator(TTR("Named Separator"));
+
+	PopupMenu *test_submenu = memnew(PopupMenu);
+	test_menu_button->get_popup()->add_submenu_node_item(TTR("Submenu"), test_submenu);
+	test_submenu->add_item(TTR("Subitem 1"));
+	test_submenu->add_item(TTR("Subitem 2"));
+	first_vb->add_child(test_menu_button);
+
+	OptionButton *test_option_button = memnew(OptionButton);
+	test_option_button->add_item("OptionButton");
+	test_option_button->add_separator();
+	test_option_button->add_item(TTR("Has"));
+	test_option_button->add_item(TTR("Many"));
+	test_option_button->add_item(TTR("Options"));
+	first_vb->add_child(test_option_button);
+	test_color_picker_button = memnew(ColorPickerButton);
+	first_vb->add_child(test_color_picker_button);
+
+	VBoxContainer *second_vb = memnew(VBoxContainer);
+	second_vb->set_h_size_flags(SIZE_EXPAND_FILL);
+	main_hb->add_child(second_vb);
+	second_vb->add_theme_constant_override("separation", 10 * EDSCALE);
+	LineEdit *le = memnew(LineEdit);
+	le->set_text("LineEdit");
+	second_vb->add_child(le);
+	le = memnew(LineEdit);
+	le->set_text(TTR("Disabled LineEdit"));
+	le->set_editable(false);
+	second_vb->add_child(le);
+	TextEdit *te = memnew(TextEdit);
+	te->set_text("TextEdit");
+	te->set_custom_minimum_size(Size2(0, 100) * EDSCALE);
+	second_vb->add_child(te);
+	second_vb->add_child(memnew(SpinBox));
+
+	HBoxContainer *vhb = memnew(HBoxContainer);
+	second_vb->add_child(vhb);
+	vhb->set_custom_minimum_size(Size2(0, 100) * EDSCALE);
+	vhb->add_child(memnew(VSlider));
+	VScrollBar *vsb = memnew(VScrollBar);
+	vsb->set_page(25);
+	vhb->add_child(vsb);
+	vhb->add_child(memnew(VSeparator));
+	VBoxContainer *hvb = memnew(VBoxContainer);
+	vhb->add_child(hvb);
+	hvb->set_alignment(BoxContainer::ALIGNMENT_CENTER);
+	hvb->set_h_size_flags(SIZE_EXPAND_FILL);
+	hvb->add_child(memnew(HSlider));
+	HScrollBar *hsb = memnew(HScrollBar);
+	hsb->set_page(25);
+	hvb->add_child(hsb);
+	HSlider *hs = memnew(HSlider);
+	hs->set_editable(false);
+	hvb->add_child(hs);
+	hvb->add_child(memnew(HSeparator));
+	ProgressBar *pb = memnew(ProgressBar);
+	pb->set_value(50);
+	hvb->add_child(pb);
+
+	VBoxContainer *third_vb = memnew(VBoxContainer);
+	third_vb->set_h_size_flags(SIZE_EXPAND_FILL);
+	third_vb->add_theme_constant_override("separation", 10 * EDSCALE);
+	main_hb->add_child(third_vb);
+
+	TabContainer *tc = memnew(TabContainer);
+	third_vb->add_child(tc);
+	tc->set_custom_minimum_size(Size2(0, 135) * EDSCALE);
+	Control *tcc = memnew(Control);
+	tcc->set_name(TTR("Tab 1"));
+	tc->add_child(tcc);
+	tcc = memnew(Control);
+	tcc->set_name(TTR("Tab 2"));
+	tc->add_child(tcc);
+	tcc = memnew(Control);
+	tcc->set_name(TTR("Tab 3"));
+	tc->add_child(tcc);
+	tc->set_tab_disabled(2, true);
+
+	Tree *test_tree = memnew(Tree);
+	third_vb->add_child(test_tree);
+	test_tree->set_custom_minimum_size(Size2(0, 175) * EDSCALE);
+
+	TreeItem *item = test_tree->create_item();
+	item->set_text(0, "Tree");
+	item = test_tree->create_item(test_tree->get_root());
+	item->set_text(0, "Item");
+	item = test_tree->create_item(test_tree->get_root());
+	item->set_editable(0, true);
+	item->set_text(0, TTR("Editable Item"));
+	TreeItem *sub_tree = test_tree->create_item(test_tree->get_root());
+	sub_tree->set_text(0, TTR("Subtree"));
+	item = test_tree->create_item(sub_tree);
+	item->set_cell_mode(0, TreeItem::CELL_MODE_CHECK);
+	item->set_editable(0, true);
+	item->set_text(0, "Check Item");
+	item = test_tree->create_item(sub_tree);
+	item->set_cell_mode(0, TreeItem::CELL_MODE_RANGE);
+	item->set_editable(0, true);
+	item->set_range_config(0, 0, 20, 0.1);
+	item->set_range(0, 2);
+	item = test_tree->create_item(sub_tree);
+	item->set_cell_mode(0, TreeItem::CELL_MODE_RANGE);
+	item->set_editable(0, true);
+	item->set_text(0, TTR("Has,Many,Options"));
+	item->set_range(0, 2);
+}
+
+void SceneThemeEditorPreview::_reload_scene() {
+	if (loaded_scene.is_null()) {
+		return;
+	}
+
+	if (loaded_scene->get_path().is_empty() || !ResourceLoader::exists(loaded_scene->get_path())) {
+		EditorNode::get_singleton()->show_warning(TTR("Invalid path, the PackedScene resource was probably moved or removed."));
+		emit_signal(SNAME("scene_invalidated"));
+		return;
+	}
+
+	for (int i = preview_content->get_child_count() - 1; i >= 0; i--) {
+		Node *node = preview_content->get_child(i);
+		node->queue_free();
+		preview_content->remove_child(node);
+	}
+
+	Node *instance = loaded_scene->instantiate();
+	if (!instance || !Object::cast_to<Control>(instance)) {
+		EditorNode::get_singleton()->show_warning(TTR("Invalid PackedScene resource, must have a Control node at its root."));
+		emit_signal(SNAME("scene_invalidated"));
+		return;
+	}
+
+	preview_content->add_child(instance);
+	emit_signal(SNAME("scene_reloaded"));
+}
+
+void SceneThemeEditorPreview::_notification(int p_what) {
+	switch (p_what) {
+		case NOTIFICATION_THEME_CHANGED: {
+			reload_scene_button->set_button_icon(get_editor_theme_icon(SNAME("Reload")));
+		} break;
+	}
+}
+
+void SceneThemeEditorPreview::_bind_methods() {
+	ADD_SIGNAL(MethodInfo("scene_invalidated"));
+	ADD_SIGNAL(MethodInfo("scene_reloaded"));
+}
+
+bool SceneThemeEditorPreview::set_preview_scene(const String &p_path) {
+	loaded_scene = ResourceLoader::load(p_path);
+	if (loaded_scene.is_null()) {
+		EditorNode::get_singleton()->show_warning(TTR("Invalid file, not a PackedScene resource."));
+		return false;
+	}
+
+	Node *instance = loaded_scene->instantiate();
+
+	if (!instance) {
+		EditorNode::get_singleton()->show_warning(TTR("Invalid PackedScene resource, could not instantiate it."));
+		return false;
+	}
+
+	if (!Object::cast_to<Control>(instance)) {
+		EditorNode::get_singleton()->show_warning(TTR("Invalid PackedScene resource, must have a Control node at its root."));
+		memdelete(instance);
+		return false;
+	}
+
+	preview_content->add_child(instance);
+	return true;
+}
+
+String SceneThemeEditorPreview::get_preview_scene_path() const {
+	if (loaded_scene.is_null()) {
+		return "";
+	}
+
+	return loaded_scene->get_path();
+}
+
+SceneThemeEditorPreview::SceneThemeEditorPreview() {
+	preview_toolbar->add_child(memnew(VSeparator));
+
+	reload_scene_button = memnew(Button);
+	reload_scene_button->set_flat(true);
+	reload_scene_button->set_tooltip_text(TTR("Reload the scene to reflect its most actual state."));
+	preview_toolbar->add_child(reload_scene_button);
+	reload_scene_button->connect(SceneStringName(pressed), callable_mp(this, &SceneThemeEditorPreview::_reload_scene));
+}

editor/scene/gui/theme_editor_preview.h

@@ -0,0 +1,119 @@
+/**************************************************************************/
+/*  theme_editor_preview.h                                                */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#pragma once
+
+#include "scene/gui/box_container.h"
+#include "scene/resources/theme.h"
+
+class Button;
+class ColorPickerButton;
+class ColorRect;
+class MarginContainer;
+class ScrollContainer;
+
+class ThemeEditorPreview : public VBoxContainer {
+	GDCLASS(ThemeEditorPreview, VBoxContainer);
+
+	ScrollContainer *preview_container = nullptr;
+	MarginContainer *preview_root = nullptr;
+	ColorRect *preview_bg = nullptr;
+	MarginContainer *preview_overlay = nullptr;
+	Control *picker_overlay = nullptr;
+	Control *hovered_control = nullptr;
+
+	struct ThemeCache {
+		Ref<StyleBox> preview_picker_overlay;
+		Color preview_picker_overlay_color;
+		Ref<StyleBox> preview_picker_label;
+		Ref<Font> preview_picker_font;
+		int font_size = 16;
+	} theme_cache;
+
+	double time_left = 0;
+
+	void _propagate_redraw(Control *p_at);
+	void _refresh_interval();
+	void _preview_visibility_changed();
+
+	void _picker_button_cbk();
+	Control *_find_hovered_control(Control *p_parent, Vector2 p_mouse_position);
+
+	void _draw_picker_overlay();
+	void _gui_input_picker_overlay(const Ref<InputEvent> &p_event);
+	void _reset_picker_overlay();
+
+protected:
+	HBoxContainer *preview_toolbar = nullptr;
+	MarginContainer *preview_content = nullptr;
+	Button *picker_button = nullptr;
+
+	void add_preview_overlay(Control *p_overlay);
+
+	void _notification(int p_what);
+	static void _bind_methods();
+
+public:
+	void set_preview_theme(const Ref<Theme> &p_theme);
+
+	ThemeEditorPreview();
+};
+
+class DefaultThemeEditorPreview : public ThemeEditorPreview {
+	GDCLASS(DefaultThemeEditorPreview, ThemeEditorPreview);
+
+	ColorPickerButton *test_color_picker_button = nullptr;
+
+protected:
+	void _notification(int p_what);
+
+public:
+	DefaultThemeEditorPreview();
+};
+
+class SceneThemeEditorPreview : public ThemeEditorPreview {
+	GDCLASS(SceneThemeEditorPreview, ThemeEditorPreview);
+
+	Ref<PackedScene> loaded_scene;
+
+	Button *reload_scene_button = nullptr;
+
+	void _reload_scene();
+
+protected:
+	void _notification(int p_what);
+	static void _bind_methods();
+
+public:
+	bool set_preview_scene(const String &p_path);
+	String get_preview_scene_path() const;
+
+	SceneThemeEditorPreview();
+};