Fix Theme type group naming in the inspector

scene/resources/theme.cpp

@@ -198,7 +198,15 @@ void Theme::_get_property_list(List<PropertyInfo> *p_list) const {
 
 	// Sort and store properties.
 	list.sort();
+	String prev_type;
 	for (const PropertyInfo &E : list) {
+		// Add groups for types so that their names are left unchanged in the inspector.
+		String current_type = E.name.get_slice("/", 0);
+		if (prev_type != current_type) {
+			p_list->push_back(PropertyInfo(Variant::NIL, current_type, PROPERTY_HINT_NONE, current_type + "/", PROPERTY_USAGE_GROUP));
+			prev_type = current_type;
+		}
+
 		p_list->push_back(E);
 	}
 }