### Godot version

4.1.1

### System information

linux

### Issue description

[simplescreenrecorder-2023-08-30_15.01.51.webm](https://github.com/godotengine/godot-proposals/assets/71937306/537d92b9-4f98-4fe6-adf4-71297be0471a)

I guess this wasn't the case before since I could save a layout named "2 monitors".

### Steps to reproduce

press space

### Minimal reproduction project

none
EditorUndoRedoManager *ur = EditorUndoRedoManager::get_singleton();
	ur->create_action(TTR("Set Stylebox Item in Theme"));
	ur->add_do_method(*edited_theme, "set_stylebox", p_item_name, edited_type, p_value.is_valid() ? p_value : Ref<StyleBox>());
	if (edited_theme->has_stylebox(p_item_name, edited_type)) {
		ur->add_undo_method(*edited_theme, "set_stylebox", p_item_name, edited_type, edited_theme->get_stylebox(p_item_name, edited_type));
	} else {
		ur->add_undo_method(*edited_theme, "set_stylebox", p_item_name, edited_type, Ref<StyleBox>());
	}
	ur->add_do_method(this, "_change_pinned_stylebox");
	ur->add_undo_method(this, "_change_pinned_stylebox");
	ur->add_do_method(this, "call_deferred", "_update_type_items");
	ur->add_undo_method(this, "call_deferred", "_update_type_items");
	ur->commit_action();
}
void ThemeTypeEditor::_change_pinned_stylebox() {
	if (leading_stylebox.pinned) {
		if (leading_stylebox.stylebox.is_valid()) {
			leading_stylebox.stylebox->disconnect_changed(callable_mp(this, &ThemeTypeEditor::_update_stylebox_from_leading));
		}
		Ref<StyleBox> new_stylebox = edited_theme->get_stylebox(leading_stylebox.item_name, edited_type);
		leading_stylebox.stylebox = new_stylebox;
		leading_stylebox.ref_stylebox = (new_stylebox.is_valid() ? new_stylebox->duplicate() : Ref<Resource>());
		if (leading_stylebox.stylebox.is_valid()) {
			new_stylebox->connect_changed(callable_mp(this, &ThemeTypeEditor::_update_stylebox_from_leading));
		}
	} else if (leading_stylebox.stylebox.is_valid()) {
		leading_stylebox.stylebox->disconnect_changed(callable_mp(this, &ThemeTypeEditor::_update_stylebox_from_leading));
	}
}
void ThemeTypeEditor::_on_pin_leader_button_pressed(Control *p_editor, String p_item_name) {