Reorganize Theme resource code for better maintainability

2 files changed, 434 insertions, 413 deletions

diff --git a/scene/resources/theme.cpp b/scene/resources/theme.cpp
index e49d883ba4..dab08d48c2 100644
--- a/scene/resources/theme.cpp
+++ b/scene/resources/theme.cpp
@@ -29,270 +29,19 @@
 /*************************************************************************/
 
 #include "theme.h"
-#include "core/io/file_access.h"
 #include "core/string/print_string.h"
 
-void Theme::_emit_theme_changed() {
-	if (no_change_propagation) {
-		return;
-	}
-
-	notify_property_list_changed();
-	emit_changed();
-}
-
-Vector<String> Theme::_get_icon_list(const String &p_theme_type) const {
-	Vector<String> ilret;
-	List<StringName> il;
-
-	get_icon_list(p_theme_type, &il);
-	ilret.resize(il.size());
-
-	int i = 0;
-	String *w = ilret.ptrw();
-	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
-		w[i] = E->get();
-	}
-	return ilret;
-}
-
-Vector<String> Theme::_get_icon_type_list() const {
-	Vector<String> ilret;
-	List<StringName> il;
-
-	get_icon_type_list(&il);
-	ilret.resize(il.size());
-
-	int i = 0;
-	String *w = ilret.ptrw();
-	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
-		w[i] = E->get();
-	}
-	return ilret;
-}
-
-Vector<String> Theme::_get_stylebox_list(const String &p_theme_type) const {
-	Vector<String> ilret;
-	List<StringName> il;
-
-	get_stylebox_list(p_theme_type, &il);
-	ilret.resize(il.size());
-
-	int i = 0;
-	String *w = ilret.ptrw();
-	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
-		w[i] = E->get();
-	}
-	return ilret;
-}
-
-Vector<String> Theme::_get_stylebox_type_list() const {
-	Vector<String> ilret;
-	List<StringName> il;
-
-	get_stylebox_type_list(&il);
-	ilret.resize(il.size());
-
-	int i = 0;
-	String *w = ilret.ptrw();
-	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
-		w[i] = E->get();
-	}
-	return ilret;
-}
-
-Vector<String> Theme::_get_font_list(const String &p_theme_type) const {
-	Vector<String> ilret;
-	List<StringName> il;
-
-	get_font_list(p_theme_type, &il);
-	ilret.resize(il.size());
-
-	int i = 0;
-	String *w = ilret.ptrw();
-	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
-		w[i] = E->get();
-	}
-	return ilret;
-}
-
-Vector<String> Theme::_get_font_type_list() const {
-	Vector<String> ilret;
-	List<StringName> il;
-
-	get_font_type_list(&il);
-	ilret.resize(il.size());
-
-	int i = 0;
-	String *w = ilret.ptrw();
-	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
-		w[i] = E->get();
-	}
-	return ilret;
-}
-
-Vector<String> Theme::_get_font_size_list(const String &p_theme_type) const {
-	Vector<String> ilret;
-	List<StringName> il;
-
-	get_font_size_list(p_theme_type, &il);
-	ilret.resize(il.size());
-
-	int i = 0;
-	String *w = ilret.ptrw();
-	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
-		w[i] = E->get();
-	}
-	return ilret;
-}
-
-Vector<String> Theme::_get_font_size_type_list() const {
-	Vector<String> ilret;
-	List<StringName> il;
-
-	get_font_size_type_list(&il);
-	ilret.resize(il.size());
-
-	int i = 0;
-	String *w = ilret.ptrw();
-	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
-		w[i] = E->get();
-	}
-	return ilret;
-}
-
-Vector<String> Theme::_get_color_list(const String &p_theme_type) const {
-	Vector<String> ilret;
-	List<StringName> il;
-
-	get_color_list(p_theme_type, &il);
-	ilret.resize(il.size());
-
-	int i = 0;
-	String *w = ilret.ptrw();
-	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
-		w[i] = E->get();
-	}
-	return ilret;
-}
-
-Vector<String> Theme::_get_color_type_list() const {
-	Vector<String> ilret;
-	List<StringName> il;
-
-	get_color_type_list(&il);
-	ilret.resize(il.size());
-
-	int i = 0;
-	String *w = ilret.ptrw();
-	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
-		w[i] = E->get();
-	}
-	return ilret;
-}
-
-Vector<String> Theme::_get_constant_list(const String &p_theme_type) const {
-	Vector<String> ilret;
-	List<StringName> il;
-
-	get_constant_list(p_theme_type, &il);
-	ilret.resize(il.size());
-
-	int i = 0;
-	String *w = ilret.ptrw();
-	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
-		w[i] = E->get();
-	}
-	return ilret;
-}
-
-Vector<String> Theme::_get_constant_type_list() const {
-	Vector<String> ilret;
-	List<StringName> il;
-
-	get_constant_type_list(&il);
-	ilret.resize(il.size());
-
-	int i = 0;
-	String *w = ilret.ptrw();
-	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
-		w[i] = E->get();
-	}
-	return ilret;
-}
-
-Vector<String> Theme::_get_theme_item_list(DataType p_data_type, const String &p_theme_type) const {
-	switch (p_data_type) {
-		case DATA_TYPE_COLOR:
-			return _get_color_list(p_theme_type);
-		case DATA_TYPE_CONSTANT:
-			return _get_constant_list(p_theme_type);
-		case DATA_TYPE_FONT:
-			return _get_font_list(p_theme_type);
-		case DATA_TYPE_FONT_SIZE:
-			return _get_font_size_list(p_theme_type);
-		case DATA_TYPE_ICON:
-			return _get_icon_list(p_theme_type);
-		case DATA_TYPE_STYLEBOX:
-			return _get_stylebox_list(p_theme_type);
-		case DATA_TYPE_MAX:
-			break; // Can't happen, but silences warning.
-	}
-
-	return Vector<String>();
-}
-
-Vector<String> Theme::_get_theme_item_type_list(DataType p_data_type) const {
-	switch (p_data_type) {
-		case DATA_TYPE_COLOR:
-			return _get_color_type_list();
-		case DATA_TYPE_CONSTANT:
-			return _get_constant_type_list();
-		case DATA_TYPE_FONT:
-			return _get_font_type_list();
-		case DATA_TYPE_FONT_SIZE:
-			return _get_font_size_type_list();
-		case DATA_TYPE_ICON:
-			return _get_icon_type_list();
-		case DATA_TYPE_STYLEBOX:
-			return _get_stylebox_type_list();
-		case DATA_TYPE_MAX:
-			break; // Can't happen, but silences warning.
-	}
-
-	return Vector<String>();
-}
-
-Vector<String> Theme::_get_type_variation_list(const StringName &p_theme_type) const {
-	Vector<String> ilret;
-	List<StringName> il;
-
-	get_type_variation_list(p_theme_type, &il);
-	ilret.resize(il.size());
-
-	int i = 0;
-	String *w = ilret.ptrw();
-	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
-		w[i] = E->get();
-	}
-	return ilret;
-}
-
-Vector<String> Theme::_get_type_list() const {
-	Vector<String> ilret;
-	List<StringName> il;
-
-	get_type_list(&il);
-	ilret.resize(il.size());
+// Universal Theme resources used when no other theme has the item.
+Ref<Theme> Theme::default_theme;
+Ref<Theme> Theme::project_default_theme;
 
-	int i = 0;
-	String *w = ilret.ptrw();
-	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
-		w[i] = E->get();
-	}
-	return ilret;
-}
+// Universal default values, final fallback for every theme.
+Ref<Texture2D> Theme::default_icon;
+Ref<StyleBox> Theme::default_style;
+Ref<Font> Theme::default_font;
+int Theme::default_font_size = 16;
 
+// Dynamic properties.
 bool Theme::_set(const StringName &p_name, const Variant &p_value) {
 	String sname = p_name;
 
@@ -452,6 +201,41 @@ void Theme::_get_property_list(List<PropertyInfo> *p_list) const {
 	}
 }
 
+// Universal fallback Theme resources.
+Ref<Theme> Theme::get_default() {
+	return default_theme;
+}
+
+void Theme::set_default(const Ref<Theme> &p_default) {
+	default_theme = p_default;
+}
+
+Ref<Theme> Theme::get_project_default() {
+	return project_default_theme;
+}
+
+void Theme::set_project_default(const Ref<Theme> &p_project_default) {
+	project_default_theme = p_project_default;
+}
+
+// Universal fallback values for theme item types.
+void Theme::set_default_icon(const Ref<Texture2D> &p_icon) {
+	default_icon = p_icon;
+}
+
+void Theme::set_default_style(const Ref<StyleBox> &p_style) {
+	default_style = p_style;
+}
+
+void Theme::set_default_font(const Ref<Font> &p_font) {
+	default_font = p_font;
+}
+
+void Theme::set_default_font_size(int p_font_size) {
+	default_font_size = p_font_size;
+}
+
+// Fallback values for theme item types, configurable per theme.
 void Theme::set_default_theme_font(const Ref<Font> &p_default_font) {
 	if (default_theme_font == p_default_font) {
 		return;
@@ -488,45 +272,7 @@ int Theme::get_default_theme_font_size() const {
 	return default_theme_font_size;
 }
 
-Ref<Theme> Theme::project_default_theme;
-Ref<Theme> Theme::default_theme;
-Ref<Texture2D> Theme::default_icon;
-Ref<StyleBox> Theme::default_style;
-Ref<Font> Theme::default_font;
-int Theme::default_font_size = 16;
-
-Ref<Theme> Theme::get_default() {
-	return default_theme;
-}
-
-void Theme::set_default(const Ref<Theme> &p_default) {
-	default_theme = p_default;
-}
-
-Ref<Theme> Theme::get_project_default() {
-	return project_default_theme;
-}
-
-void Theme::set_project_default(const Ref<Theme> &p_project_default) {
-	project_default_theme = p_project_default;
-}
-
-void Theme::set_default_icon(const Ref<Texture2D> &p_icon) {
-	default_icon = p_icon;
-}
-
-void Theme::set_default_style(const Ref<StyleBox> &p_style) {
-	default_style = p_style;
-}
-
-void Theme::set_default_font(const Ref<Font> &p_font) {
-	default_font = p_font;
-}
-
-void Theme::set_default_font_size(int p_font_size) {
-	default_font_size = p_font_size;
-}
-
+// Icons.
 void Theme::set_icon(const StringName &p_name, const StringName &p_theme_type, const Ref<Texture2D> &p_icon) {
 	if (icon_map[p_theme_type].has(p_name) && icon_map[p_theme_type][p_name].is_valid()) {
 		icon_map[p_theme_type][p_name]->disconnect("changed", callable_mp(this, &Theme::_emit_theme_changed));
@@ -611,6 +357,7 @@ void Theme::get_icon_type_list(List<StringName> *p_list) const {
 	}
 }
 
+// Styleboxes.
 void Theme::set_stylebox(const StringName &p_name, const StringName &p_theme_type, const Ref<StyleBox> &p_style) {
 	if (style_map[p_theme_type].has(p_name) && style_map[p_theme_type][p_name].is_valid()) {
 		style_map[p_theme_type][p_name]->disconnect("changed", callable_mp(this, &Theme::_emit_theme_changed));
@@ -695,6 +442,7 @@ void Theme::get_stylebox_type_list(List<StringName> *p_list) const {
 	}
 }
 
+// Fonts.
 void Theme::set_font(const StringName &p_name, const StringName &p_theme_type, const Ref<Font> &p_font) {
 	if (font_map[p_theme_type][p_name].is_valid()) {
 		font_map[p_theme_type][p_name]->disconnect("changed", callable_mp(this, &Theme::_emit_theme_changed));
@@ -781,6 +529,7 @@ void Theme::get_font_type_list(List<StringName> *p_list) const {
 	}
 }
 
+// Font sizes.
 void Theme::set_font_size(const StringName &p_name, const StringName &p_theme_type, int p_font_size) {
 	font_size_map[p_theme_type][p_name] = p_font_size;
 
@@ -855,6 +604,7 @@ void Theme::get_font_size_type_list(List<StringName> *p_list) const {
 	}
 }
 
+// Colors.
 void Theme::set_color(const StringName &p_name, const StringName &p_theme_type, const Color &p_color) {
 	color_map[p_theme_type][p_name] = p_color;
 
@@ -927,6 +677,7 @@ void Theme::get_color_type_list(List<StringName> *p_list) const {
 	}
 }
 
+// Theme constants.
 void Theme::set_constant(const StringName &p_name, const StringName &p_theme_type, int p_constant) {
 	constant_map[p_theme_type][p_name] = p_constant;
 
@@ -999,6 +750,7 @@ void Theme::get_constant_type_list(List<StringName> *p_list) const {
 	}
 }
 
+// Generic methods for managing theme items.
 void Theme::set_theme_item(DataType p_data_type, const StringName &p_name, const StringName &p_theme_type, const Variant &p_value) {
 	switch (p_data_type) {
 		case DATA_TYPE_COLOR: {
@@ -1230,6 +982,7 @@ void Theme::get_theme_item_type_list(DataType p_data_type, List<StringName> *p_l
 	}
 }
 
+// Theme type variations.
 void Theme::set_type_variation(const StringName &p_theme_type, const StringName &p_base_type) {
 	ERR_FAIL_COND_MSG(p_theme_type == StringName(), "An empty theme type cannot be marked as a variation of another type.");
 	ERR_FAIL_COND_MSG(ClassDB::class_exists(p_theme_type), "A type associated with a built-in class cannot be marked as a variation of another type.");
@@ -1287,66 +1040,352 @@ void Theme::get_type_variation_list(const StringName &p_base_type, List<StringNa
 	}
 }
 
-void Theme::_freeze_change_propagation() {
-	no_change_propagation = true;
-}
+// Theme types.
+void Theme::get_type_list(List<StringName> *p_list) const {
+	ERR_FAIL_NULL(p_list);
 
-void Theme::_unfreeze_and_propagate_changes() {
-	no_change_propagation = false;
-	_emit_theme_changed();
+	Set<StringName> types;
+	const StringName *key = nullptr;
+
+	// Icons.
+	while ((key = icon_map.next(key))) {
+		types.insert(*key);
+	}
+
+	key = nullptr;
+
+	// StyleBoxes.
+	while ((key = style_map.next(key))) {
+		types.insert(*key);
+	}
+
+	key = nullptr;
+
+	// Fonts.
+	while ((key = font_map.next(key))) {
+		types.insert(*key);
+	}
+
+	key = nullptr;
+
+	// Font sizes.
+	while ((key = font_size_map.next(key))) {
+		types.insert(*key);
+	}
+
+	key = nullptr;
+
+	// Colors.
+	while ((key = color_map.next(key))) {
+		types.insert(*key);
+	}
+
+	key = nullptr;
+
+	// Constants.
+	while ((key = constant_map.next(key))) {
+		types.insert(*key);
+	}
+
+	for (Set<StringName>::Element *E = types.front(); E; E = E->next()) {
+		p_list->push_back(E->get());
+	}
 }
 
-void Theme::clear() {
-	// These items need disconnecting.
-	{
-		const StringName *K = nullptr;
-		while ((K = icon_map.next(K))) {
-			const StringName *L = nullptr;
-			while ((L = icon_map[*K].next(L))) {
-				Ref<Texture2D> icon = icon_map[*K][*L];
-				if (icon.is_valid()) {
-					icon->disconnect("changed", callable_mp(this, &Theme::_emit_theme_changed));
-				}
+void Theme::get_type_dependencies(const StringName &p_base_type, const StringName &p_type_variation, List<StringName> *p_list) {
+	ERR_FAIL_NULL(p_list);
+
+	// Build the dependency chain for type variations.
+	if (p_type_variation != StringName()) {
+		StringName variation_name = p_type_variation;
+		while (variation_name != StringName()) {
+			p_list->push_back(variation_name);
+			variation_name = get_type_variation_base(variation_name);
+
+			// If we have reached the base type dependency, it's safe to stop (assuming no funny business was done to the Theme).
+			if (variation_name == p_base_type) {
+				break;
 			}
 		}
 	}
 
-	{
-		const StringName *K = nullptr;
-		while ((K = style_map.next(K))) {
-			const StringName *L = nullptr;
-			while ((L = style_map[*K].next(L))) {
-				Ref<StyleBox> style = style_map[*K][*L];
-				if (style.is_valid()) {
-					style->disconnect("changed", callable_mp(this, &Theme::_emit_theme_changed));
-				}
-			}
-		}
+	// Continue building the chain using native class hierarchy.
+	StringName class_name = p_base_type;
+	while (class_name != StringName()) {
+		p_list->push_back(class_name);
+		class_name = ClassDB::get_parent_class_nocheck(class_name);
 	}
+}
 
-	{
-		const StringName *K = nullptr;
-		while ((K = font_map.next(K))) {
-			const StringName *L = nullptr;
-			while ((L = font_map[*K].next(L))) {
-				Ref<Font> font = font_map[*K][*L];
-				if (font.is_valid()) {
-					font->disconnect("changed", callable_mp(this, &Theme::_emit_theme_changed));
-				}
-			}
-		}
+// Internal methods for getting lists as a Vector of String (compatible with public API).
+Vector<String> Theme::_get_icon_list(const String &p_theme_type) const {
+	Vector<String> ilret;
+	List<StringName> il;
+
+	get_icon_list(p_theme_type, &il);
+	ilret.resize(il.size());
+
+	int i = 0;
+	String *w = ilret.ptrw();
+	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
+		w[i] = E->get();
 	}
+	return ilret;
+}
 
-	icon_map.clear();
-	style_map.clear();
-	font_map.clear();
-	font_size_map.clear();
-	color_map.clear();
-	constant_map.clear();
+Vector<String> Theme::_get_icon_type_list() const {
+	Vector<String> ilret;
+	List<StringName> il;
 
-	variation_map.clear();
-	variation_base_map.clear();
+	get_icon_type_list(&il);
+	ilret.resize(il.size());
+
+	int i = 0;
+	String *w = ilret.ptrw();
+	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
+		w[i] = E->get();
+	}
+	return ilret;
+}
+
+Vector<String> Theme::_get_stylebox_list(const String &p_theme_type) const {
+	Vector<String> ilret;
+	List<StringName> il;
+
+	get_stylebox_list(p_theme_type, &il);
+	ilret.resize(il.size());
+
+	int i = 0;
+	String *w = ilret.ptrw();
+	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
+		w[i] = E->get();
+	}
+	return ilret;
+}
+
+Vector<String> Theme::_get_stylebox_type_list() const {
+	Vector<String> ilret;
+	List<StringName> il;
+
+	get_stylebox_type_list(&il);
+	ilret.resize(il.size());
+
+	int i = 0;
+	String *w = ilret.ptrw();
+	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
+		w[i] = E->get();
+	}
+	return ilret;
+}
+
+Vector<String> Theme::_get_font_list(const String &p_theme_type) const {
+	Vector<String> ilret;
+	List<StringName> il;
+
+	get_font_list(p_theme_type, &il);
+	ilret.resize(il.size());
+
+	int i = 0;
+	String *w = ilret.ptrw();
+	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
+		w[i] = E->get();
+	}
+	return ilret;
+}
+
+Vector<String> Theme::_get_font_type_list() const {
+	Vector<String> ilret;
+	List<StringName> il;
+
+	get_font_type_list(&il);
+	ilret.resize(il.size());
+
+	int i = 0;
+	String *w = ilret.ptrw();
+	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
+		w[i] = E->get();
+	}
+	return ilret;
+}
+
+Vector<String> Theme::_get_font_size_list(const String &p_theme_type) const {
+	Vector<String> ilret;
+	List<StringName> il;
+
+	get_font_size_list(p_theme_type, &il);
+	ilret.resize(il.size());
+
+	int i = 0;
+	String *w = ilret.ptrw();
+	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
+		w[i] = E->get();
+	}
+	return ilret;
+}
+
+Vector<String> Theme::_get_font_size_type_list() const {
+	Vector<String> ilret;
+	List<StringName> il;
+
+	get_font_size_type_list(&il);
+	ilret.resize(il.size());
+
+	int i = 0;
+	String *w = ilret.ptrw();
+	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
+		w[i] = E->get();
+	}
+	return ilret;
+}
+
+Vector<String> Theme::_get_color_list(const String &p_theme_type) const {
+	Vector<String> ilret;
+	List<StringName> il;
+
+	get_color_list(p_theme_type, &il);
+	ilret.resize(il.size());
+
+	int i = 0;
+	String *w = ilret.ptrw();
+	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
+		w[i] = E->get();
+	}
+	return ilret;
+}
+
+Vector<String> Theme::_get_color_type_list() const {
+	Vector<String> ilret;
+	List<StringName> il;
+
+	get_color_type_list(&il);
+	ilret.resize(il.size());
+
+	int i = 0;
+	String *w = ilret.ptrw();
+	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
+		w[i] = E->get();
+	}
+	return ilret;
+}
+
+Vector<String> Theme::_get_constant_list(const String &p_theme_type) const {
+	Vector<String> ilret;
+	List<StringName> il;
+
+	get_constant_list(p_theme_type, &il);
+	ilret.resize(il.size());
+
+	int i = 0;
+	String *w = ilret.ptrw();
+	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
+		w[i] = E->get();
+	}
+	return ilret;
+}
+
+Vector<String> Theme::_get_constant_type_list() const {
+	Vector<String> ilret;
+	List<StringName> il;
+
+	get_constant_type_list(&il);
+	ilret.resize(il.size());
 
+	int i = 0;
+	String *w = ilret.ptrw();
+	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
+		w[i] = E->get();
+	}
+	return ilret;
+}
+
+Vector<String> Theme::_get_theme_item_list(DataType p_data_type, const String &p_theme_type) const {
+	switch (p_data_type) {
+		case DATA_TYPE_COLOR:
+			return _get_color_list(p_theme_type);
+		case DATA_TYPE_CONSTANT:
+			return _get_constant_list(p_theme_type);
+		case DATA_TYPE_FONT:
+			return _get_font_list(p_theme_type);
+		case DATA_TYPE_FONT_SIZE:
+			return _get_font_size_list(p_theme_type);
+		case DATA_TYPE_ICON:
+			return _get_icon_list(p_theme_type);
+		case DATA_TYPE_STYLEBOX:
+			return _get_stylebox_list(p_theme_type);
+		case DATA_TYPE_MAX:
+			break; // Can't happen, but silences warning.
+	}
+
+	return Vector<String>();
+}
+
+Vector<String> Theme::_get_theme_item_type_list(DataType p_data_type) const {
+	switch (p_data_type) {
+		case DATA_TYPE_COLOR:
+			return _get_color_type_list();
+		case DATA_TYPE_CONSTANT:
+			return _get_constant_type_list();
+		case DATA_TYPE_FONT:
+			return _get_font_type_list();
+		case DATA_TYPE_FONT_SIZE:
+			return _get_font_size_type_list();
+		case DATA_TYPE_ICON:
+			return _get_icon_type_list();
+		case DATA_TYPE_STYLEBOX:
+			return _get_stylebox_type_list();
+		case DATA_TYPE_MAX:
+			break; // Can't happen, but silences warning.
+	}
+
+	return Vector<String>();
+}
+
+Vector<String> Theme::_get_type_variation_list(const StringName &p_theme_type) const {
+	Vector<String> ilret;
+	List<StringName> il;
+
+	get_type_variation_list(p_theme_type, &il);
+	ilret.resize(il.size());
+
+	int i = 0;
+	String *w = ilret.ptrw();
+	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
+		w[i] = E->get();
+	}
+	return ilret;
+}
+
+Vector<String> Theme::_get_type_list() const {
+	Vector<String> ilret;
+	List<StringName> il;
+
+	get_type_list(&il);
+	ilret.resize(il.size());
+
+	int i = 0;
+	String *w = ilret.ptrw();
+	for (List<StringName>::Element *E = il.front(); E; E = E->next(), i++) {
+		w[i] = E->get();
+	}
+	return ilret;
+}
+
+// Theme bulk manipulations.
+void Theme::_emit_theme_changed() {
+	if (no_change_propagation) {
+		return;
+	}
+
+	notify_property_list_changed();
+	emit_changed();
+}
+
+void Theme::_freeze_change_propagation() {
+	no_change_propagation = true;
+}
+
+void Theme::_unfreeze_and_propagate_changes() {
+	no_change_propagation = false;
 	_emit_theme_changed();
 }
 
@@ -1434,80 +1473,58 @@ void Theme::merge_with(const Ref<Theme> &p_other) {
 	_unfreeze_and_propagate_changes();
 }
 
-void Theme::get_type_list(List<StringName> *p_list) const {
-	ERR_FAIL_NULL(p_list);
-
-	Set<StringName> types;
-	const StringName *key = nullptr;
-
-	// Icons.
-	while ((key = icon_map.next(key))) {
-		types.insert(*key);
-	}
-
-	key = nullptr;
-
-	// StyleBoxes.
-	while ((key = style_map.next(key))) {
-		types.insert(*key);
-	}
-
-	key = nullptr;
-
-	// Fonts.
-	while ((key = font_map.next(key))) {
-		types.insert(*key);
-	}
-
-	key = nullptr;
-
-	// Font sizes.
-	while ((key = font_size_map.next(key))) {
-		types.insert(*key);
-	}
-
-	key = nullptr;
-
-	// Colors.
-	while ((key = color_map.next(key))) {
-		types.insert(*key);
-	}
-
-	key = nullptr;
-
-	// Constants.
-	while ((key = constant_map.next(key))) {
-		types.insert(*key);
+void Theme::clear() {
+	// These items need disconnecting.
+	{
+		const StringName *K = nullptr;
+		while ((K = icon_map.next(K))) {
+			const StringName *L = nullptr;
+			while ((L = icon_map[*K].next(L))) {
+				Ref<Texture2D> icon = icon_map[*K][*L];
+				if (icon.is_valid()) {
+					icon->disconnect("changed", callable_mp(this, &Theme::_emit_theme_changed));
+				}
+			}
+		}
 	}
 
-	for (Set<StringName>::Element *E = types.front(); E; E = E->next()) {
-		p_list->push_back(E->get());
+	{
+		const StringName *K = nullptr;
+		while ((K = style_map.next(K))) {
+			const StringName *L = nullptr;
+			while ((L = style_map[*K].next(L))) {
+				Ref<StyleBox> style = style_map[*K][*L];
+				if (style.is_valid()) {
+					style->disconnect("changed", callable_mp(this, &Theme::_emit_theme_changed));
+				}
+			}
+		}
 	}
-}
-
-void Theme::get_type_dependencies(const StringName &p_base_type, const StringName &p_type_variation, List<StringName> *p_list) {
-	ERR_FAIL_NULL(p_list);
 
-	// Build the dependency chain for type variations.
-	if (p_type_variation != StringName()) {
-		StringName variation_name = p_type_variation;
-		while (variation_name != StringName()) {
-			p_list->push_back(variation_name);
-			variation_name = get_type_variation_base(variation_name);
-
-			// If we have reached the base type dependency, it's safe to stop (assuming no funny business was done to the Theme).
-			if (variation_name == p_base_type) {
-				break;
+	{
+		const StringName *K = nullptr;
+		while ((K = font_map.next(K))) {
+			const StringName *L = nullptr;
+			while ((L = font_map[*K].next(L))) {
+				Ref<Font> font = font_map[*K][*L];
+				if (font.is_valid()) {
+					font->disconnect("changed", callable_mp(this, &Theme::_emit_theme_changed));
+				}
 			}
 		}
 	}
 
-	// Continue building the chain using native class hierarchy.
-	StringName class_name = p_base_type;
-	while (class_name != StringName()) {
-		p_list->push_back(class_name);
-		class_name = ClassDB::get_parent_class_nocheck(class_name);
-	}
+	icon_map.clear();
+	style_map.clear();
+	font_map.clear();
+	font_size_map.clear();
+	color_map.clear();
+	constant_map.clear();
+
+	variation_map.clear();
+	variation_base_map.clear();
+
+	_emit_theme_changed();
 }
 
 void Theme::reset_state() {
diff --git a/scene/resources/theme.h b/scene/resources/theme.h
index 15f21b91b8..35e466f899 100644
--- a/scene/resources/theme.h
+++ b/scene/resources/theme.h
@@ -96,13 +96,17 @@ protected:
 	bool _get(const StringName &p_name, Variant &r_ret) const;
 	void _get_property_list(List<PropertyInfo> *p_list) const;
 
-	static Ref<Theme> project_default_theme;
+	// Universal Theme resources used when no other theme has the item.
 	static Ref<Theme> default_theme;
+	static Ref<Theme> project_default_theme;
+
+	// Universal default values, final fallback for every theme.
 	static Ref<Texture2D> default_icon;
 	static Ref<StyleBox> default_style;
 	static Ref<Font> default_font;
 	static int default_font_size;
 
+	// Default values configurable for each individual theme.
 	Ref<Font> default_theme_font;
 	int default_theme_font_size = -1;