Add sticky tree item support

Author: dugramen

doc/classes/EditorSettings.xml

@@ -983,6 +983,9 @@
 			Expanding main editor window content to the title, if supported by [DisplayServer]. See [constant DisplayServer.WINDOW_FLAG_EXTEND_TO_TITLE].
 			Specific to the macOS platform.
 		</member>
+		<member name="interface/editor/appearance/max_sticky_tree_items" type="int" setter="" getter="">
+			The maximum number of tree items allowed to stick to the top while its children are in view. A value of [code]0[/code] disables sticking.
+		</member>
 		<member name="interface/editor/appearance/project_manager_screen" type="int" setter="" getter="">
 			The preferred monitor to display the project manager.
 		</member>

doc/classes/Tree.xml

@@ -650,6 +650,9 @@
 		<theme_item name="scroll_border" data_type="constant" type="int" default="4">
 			The maximum distance between the mouse cursor and the control's border to trigger border scrolling when dragging.
 		</theme_item>
+		<theme_item name="scroll_max_sticky_items" data_type="constant" type="int" default="0">
+			The maximum number of tree items allowed to stick to the top while its children are in view. A value of [code]0[/code] disables sticking.
+		</theme_item>
 		<theme_item name="scroll_speed" data_type="constant" type="int" default="12">
 			The speed of border scrolling.
 		</theme_item>

editor/settings/editor_settings.cpp

@@ -59,7 +59,6 @@
 #include "scene/gui/file_dialog.h"
 #include "scene/main/node.h"
 #include "scene/main/scene_tree.h"
-#include "scene/main/window.h"
 #include "scene/resources/animation.h"
 #include "servers/display/display_server.h"
 
@@ -506,6 +505,7 @@ void EditorSettings::_load_defaults(Ref<ConfigFile> p_extra_config) {
 	EDITOR_SETTING_USAGE(Variant::BOOL, PROPERTY_HINT_NONE, "interface/editor/appearance/use_embedded_menu", false, "", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_EDITOR_BASIC_SETTING)
 	EDITOR_SETTING_USAGE(Variant::BOOL, PROPERTY_HINT_NONE, "interface/editor/appearance/use_native_file_dialogs", false, "", PROPERTY_USAGE_DEFAULT)
 	EDITOR_SETTING_USAGE(Variant::BOOL, PROPERTY_HINT_NONE, "interface/editor/appearance/expand_to_title", true, "", PROPERTY_USAGE_DEFAULT | PROPERTY_USAGE_RESTART_IF_CHANGED | PROPERTY_USAGE_EDITOR_BASIC_SETTING)
+	EDITOR_SETTING_BASIC(Variant::INT, PROPERTY_HINT_RANGE, "interface/editor/appearance/max_sticky_tree_items", 6, "0,16")
 
 	EDITOR_SETTING_BASIC(Variant::INT, PROPERTY_HINT_RANGE, "interface/editor/fonts/main_font_size", 14, "8,48,1")
 	EDITOR_SETTING_BASIC(Variant::INT, PROPERTY_HINT_RANGE, "interface/editor/fonts/code_font_size", 14, "8,48,1")

editor/themes/editor_theme_manager.cpp

@@ -268,6 +268,7 @@ EditorThemeManager::ThemeConfiguration EditorThemeManager::_create_theme_config(
 	config.gizmo_handle_scale = EDITOR_GET("interface/touchscreen/scale_gizmo_handles");
 	config.subresource_hue_tint = EDITOR_GET("docks/property_editor/subresource_hue_tint");
 	config.dragging_hover_wait_msec = (float)EDITOR_GET("interface/editor/timers/dragging_hover_wait_seconds") * 1000;
+	config.max_sticky_tree_items = EDITOR_GET("interface/editor/appearance/max_sticky_tree_items");
 
 	// Handle theme style.
 	if (config.preset != "Custom") {
@@ -718,6 +719,7 @@ bool EditorThemeManager::is_generated_theme_outdated() {
 		// TODO: We can use this information more intelligently to do partial theme updates and speed things up.
 		outdated_cache = EditorSettings::get_singleton()->check_changed_settings_in_group("interface/theme") ||
 				EditorSettings::get_singleton()->check_changed_settings_in_group("interface/editor/fonts") ||
+				EditorSettings::get_singleton()->check_changed_settings_in_group("interface/editor/appearance/max_sticky_tree_items") ||
 				EditorSettings::get_singleton()->check_changed_settings_in_group("interface/touchscreen/enable_touch_optimizations") ||
 				EditorSettings::get_singleton()->check_changed_settings_in_group("editors/visual_editors") ||
 				EditorSettings::get_singleton()->check_changed_settings_in_group("text_editor/theme") ||

editor/themes/editor_theme_manager.h

@@ -80,6 +80,7 @@ class EditorThemeManager {
 		int inspector_property_height = 28;
 		float subresource_hue_tint = 0.0;
 		float dragging_hover_wait_msec = 0;
+		int max_sticky_tree_items = 5;
 
 		// Make sure to keep those in sync with the definitions in the editor settings.
 		const float default_icon_saturation = 2.0;

editor/themes/theme_classic.cpp

@@ -624,6 +624,7 @@ void ThemeClassic::populate_standard_styles(const Ref<EditorTheme> &p_theme, Edi
 			p_theme->set_constant("icon_h_separation", "Tree", (p_config.increased_margin + 2) * EDSCALE);
 			p_theme->set_constant("button_margin", "Tree", p_config.base_margin * EDSCALE);
 			p_theme->set_constant("dragging_unfold_wait_msec", "Tree", p_config.dragging_hover_wait_msec);
+			p_theme->set_constant("scroll_max_sticky_items", "Tree", p_config.max_sticky_tree_items);
 			p_theme->set_constant("scroll_border", "Tree", 40 * EDSCALE);
 			p_theme->set_constant("scroll_speed", "Tree", 12);
 			p_theme->set_constant("outline_size", "Tree", 0);

editor/themes/theme_modern.cpp

@@ -650,6 +650,7 @@ void ThemeModern::populate_standard_styles(const Ref<EditorTheme> &p_theme, Edit
 			p_theme->set_constant("icon_h_separation", "Tree", p_config.base_margin * 1.5 * EDSCALE);
 			p_theme->set_constant("button_margin", "Tree", p_config.base_margin * EDSCALE);
 			p_theme->set_constant("dragging_unfold_wait_msec", "Tree", p_config.dragging_hover_wait_msec);
+			p_theme->set_constant("scroll_max_sticky_items", "Tree", p_config.max_sticky_tree_items);
 			p_theme->set_constant("scroll_border", "Tree", 40 * EDSCALE);
 			p_theme->set_constant("scroll_speed", "Tree", 12);
 			p_theme->set_constant("outline_size", "Tree", 0);