diff --git a/common/include/ui.h b/common/include/ui.h
index e59efa72c..d6d7fe4ce 100644
--- a/common/include/ui.h
+++ b/common/include/ui.h
@@ -241,6 +241,8 @@ public:
 	template <typename T>
 	UI_DIALOG(short x, short y, short w, short h, enum dialog_flags flags, ui_subclass_subfunction_t<T> callback) :
 	UI_DIALOG(x, y, w, h, flags, reinterpret_cast<ui_subclass_subfunction_t<UI_DIALOG>>(callback), nullptr, nullptr) {}
+	
+	~UI_DIALOG();
 };
 
 #define B1_JUST_PRESSED     (event.type == EVENT_MOUSE_BUTTON_DOWN && event_mouse_get_button(event) == 0)
diff --git a/common/ui/dialog.cpp b/common/ui/dialog.cpp
index c704e49ce..37eb46a01 100644
--- a/common/ui/dialog.cpp
+++ b/common/ui/dialog.cpp
@@ -133,10 +133,9 @@ static window_event_result ui_dialog_handler(window *wind,const d_event &event,
 		}
 
 		case EVENT_WINDOW_CLOSE:
-			ui_gadget_delete_all(dlg);
-			selected_gadget = NULL;
-			delete dlg;
-			return window_event_result::ignored;
+			if (rval != window_event_result::deleted)	// check if handler already deleted dialog (e.g. if UI_DIALOG was subclassed)
+				delete dlg;
+			return window_event_result::ignored;	// free the window in any case (until UI_DIALOG is subclass of window)
 		default:
 			return window_event_result::ignored;
 	}
@@ -194,6 +193,12 @@ void ui_dialog_set_current_canvas(UI_DIALOG *dlg)
 	gr_set_current_canvas(window_get_canvas(*dlg->wind));
 }
 
+UI_DIALOG::~UI_DIALOG()
+{
+	ui_gadget_delete_all(this);
+	selected_gadget = NULL;
+}
+
 void ui_close_dialog( UI_DIALOG * dlg )
 {
 	window_close(dlg->wind);