Changed wxYield to wxYieldIfNeeded in PopupMenu, to avoid recursive wxYield assertions

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@9664 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/window.cpp

@@ -1470,7 +1470,7 @@ bool wxWindow::DoPopupMenu(wxMenu *menu, int x, int y)
     ::ClientToScreen(hWnd, &point);
     wxCurrentPopupMenu = menu;
     ::TrackPopupMenu(hMenu, TPM_RIGHTBUTTON, point.x, point.y, 0, hWnd, NULL);
-    wxYield();
+    wxYieldIfNeeded();
     wxCurrentPopupMenu = NULL;
 
     menu->SetInvokingWindow(NULL);