reset g_delayedFocus when the window is deleted to avoid crashes when using it

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@15240 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk1/window.cpp

@@ -2524,6 +2524,9 @@ wxWindowGTK::~wxWindowGTK()
     if (g_activeFrame == this)
         g_activeFrame = NULL;
 
+    if ( g_delayedFocus == this )
+        g_delayedFocus = NULL;
+
     m_isBeingDeleted = TRUE;
     m_hasVMT = FALSE;