Ability to safe destroy widget later by event.

src/dlangui/core/events.d

@@ -1649,6 +1649,20 @@ class RunnableEvent : CustomEvent {
     }
 }
 
+/// save destroy event
+class SafeDestroyEvent : RunnableEvent {
+    Widget _widgetToDestroy;
+    this (Widget widgetToDestroy)
+    {
+        _widgetToDestroy = widgetToDestroy;
+        super(1,null, delegate void () {
+            if (_widgetToDestroy.parent) 
+                _widgetToDestroy.parent.removeChild(_widgetToDestroy);
+            destroy(_widgetToDestroy);
+        });
+    }
+}
+
 interface CustomEventTarget {
     /// post event to handle in UI thread (this method can be used from background thread)
     void postEvent(CustomEvent event);

src/dlangui/platforms/common/platform.d

@@ -519,6 +519,12 @@ class Window : CustomEventTarget {
         destroy(_timerQueue);
         _eventList = null;
     }
+    /// safe destroy widget
+    void safeWidgetDestroy(Widget widgetToDestroy)
+    {
+        SafeDestroyEvent ev = new SafeDestroyEvent(widgetToDestroy);
+        postEvent(ev);
+    }
     
     private void animate(Widget root, long interval) {
         if (root is null)