better fix for infinite loop in HandleOnNavigationKey() when wxUSE_STL==1 and start_node is NULL

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@38241 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/common/containr.cpp

@@ -375,6 +375,12 @@ void wxControlContainer::HandleOnNavigationKey( wxNavigationKeyEvent& event )
         // Have we come to the last or first item on the panel?
         if ( !node )
         {
+            if ( !start_node )
+            {
+                // exit now as otherwise we'd loop forever
+                break;
+            }
+
             if ( !goingDown )
             {
                 // Check if our (maybe grand) parent is another panel: if this