always pass WM_DESTROY to DefWindowProc() - this fixes memory/resource leak for wxListBox

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@11447 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/window.cpp

@@ -2125,7 +2125,11 @@ long wxWindowMSW::MSWWindowProc(WXUINT message, WXWPARAM wParam, WXLPARAM lParam
             break;
 
         case WM_DESTROY:
-            processed = HandleDestroy();
+            // never set processed to TRUE and *always* pass WM_DESTROY to
+            // DefWindowProc() as Windows may do some internal cleanup when
+            // processing it and failing to pass the message along may cause
+            // memory and resource leaks!
+            (void)HandleDestroy();
             break;
 
         case WM_MOVE: