Add option to draw all tabs in front

doc/classes/TabContainer.xml

@@ -149,6 +149,9 @@
 		<member name="tabs_visible" type="bool" setter="set_tabs_visible" getter="are_tabs_visible" default="true">
 			If [code]true[/code], tabs are visible. If [code]false[/code], tabs' content and titles are hidden.
 		</member>
+		<member name="all_tabs_in_front" type="bool" setter="set_all_tabs_in_front" getter="is_all_tabs_in_front" default="false">
+			If [code]true[/code], all tabs are drawn in front of the panel. If [code]false[/code], inactive tabs are drawn behind the panel.
+		</member>
 		<member name="use_hidden_tabs_for_min_size" type="bool" setter="set_use_hidden_tabs_for_min_size" getter="get_use_hidden_tabs_for_min_size" default="false">
 			If [code]true[/code], children [Control] nodes that are hidden have their minimum size take into account in the total, instead of only the currently visible one.
 		</member>

scene/gui/tab_container.cpp

@@ -415,6 +415,11 @@ void TabContainer::_notification(int p_what) {
 					break;
 			}
 
+			if (all_tabs_in_front) {
+				// Draw the tab area.
+				panel->draw(canvas, Rect2(0, header_height, size.width, size.height - header_height));
+			}
+
 			// Draw unselected tabs in back
 			int x = 0;
 			int x_current = 0;
@@ -446,8 +451,10 @@ void TabContainer::_notification(int p_what) {
 				last_tab_cache = index;
 			}
 
-			// Draw the tab area.
-			panel->draw(canvas, Rect2(0, header_height, size.width, size.height - header_height));
+			if (!all_tabs_in_front) {
+				// Draw the tab area.
+				panel->draw(canvas, Rect2(0, header_height, size.width, size.height - header_height));
+			}
 
 			// Draw selected tab in front. only draw selected tab when it's in visible range.
 			if (tabs.size() > 0 && current - first_tab_cache < tab_widths.size() && current >= first_tab_cache) {
@@ -1017,6 +1024,20 @@ bool TabContainer::are_tabs_visible() const {
 	return tabs_visible;
 }
 
+void TabContainer::set_all_tabs_in_front(bool p_in_front) {
+	if (p_in_front == all_tabs_in_front) {
+		return;
+	}
+
+	all_tabs_in_front = p_in_front;
+
+	update();
+}
+
+bool TabContainer::is_all_tabs_in_front() const {
+	return all_tabs_in_front;
+}
+
 Control *TabContainer::_get_tab(int p_idx) const {
 	return get_tab_control(p_idx);
 }
@@ -1208,6 +1229,8 @@ void TabContainer::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("get_tab_align"), &TabContainer::get_tab_align);
 	ClassDB::bind_method(D_METHOD("set_tabs_visible", "visible"), &TabContainer::set_tabs_visible);
 	ClassDB::bind_method(D_METHOD("are_tabs_visible"), &TabContainer::are_tabs_visible);
+	ClassDB::bind_method(D_METHOD("set_all_tabs_in_front", "is_front"), &TabContainer::set_all_tabs_in_front);
+	ClassDB::bind_method(D_METHOD("is_all_tabs_in_front"), &TabContainer::is_all_tabs_in_front);
 	ClassDB::bind_method(D_METHOD("set_tab_title", "tab_idx", "title"), &TabContainer::set_tab_title);
 	ClassDB::bind_method(D_METHOD("get_tab_title", "tab_idx"), &TabContainer::get_tab_title);
 	ClassDB::bind_method(D_METHOD("set_tab_icon", "tab_idx", "icon"), &TabContainer::set_tab_icon);
@@ -1234,6 +1257,7 @@ void TabContainer::_bind_methods() {
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "tab_align", PROPERTY_HINT_ENUM, "Left,Center,Right"), "set_tab_align", "get_tab_align");
 	ADD_PROPERTY(PropertyInfo(Variant::INT, "current_tab", PROPERTY_HINT_RANGE, "-1,4096,1", PROPERTY_USAGE_EDITOR), "set_current_tab", "get_current_tab");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "tabs_visible"), "set_tabs_visible", "are_tabs_visible");
+	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "all_tabs_in_front"), "set_all_tabs_in_front", "is_all_tabs_in_front");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "drag_to_rearrange_enabled"), "set_drag_to_rearrange_enabled", "get_drag_to_rearrange_enabled");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "use_hidden_tabs_for_min_size"), "set_use_hidden_tabs_for_min_size", "get_use_hidden_tabs_for_min_size");
 
@@ -1253,6 +1277,7 @@ TabContainer::TabContainer() {
 	previous = 0;
 	align = ALIGN_CENTER;
 	tabs_visible = true;
+	all_tabs_in_front = false;
 	drag_to_rearrange_enabled = false;
 	tabs_rearrange_group = -1;
 	use_hidden_tabs_for_min_size = false;

scene/gui/tab_container.h

@@ -52,6 +52,7 @@ private:
 	int current;
 	int previous;
 	bool tabs_visible;
+	bool all_tabs_in_front;
 	bool buttons_visible_cache;
 	bool menu_hovered;
 	int highlight_arrow;
@@ -94,6 +95,9 @@ public:
 	void set_tabs_visible(bool p_visible);
 	bool are_tabs_visible() const;
 
+	void set_all_tabs_in_front(bool p_is_front);
+	bool is_all_tabs_in_front() const;
+
 	void set_tab_title(int p_tab, const String &p_title);
 	String get_tab_title(int p_tab) const;