Don't set even try to set focus to wxPopupWindow itself in wxMSW.

This doesn't work anyhow with our popup window implementation (it's a child of
the desktop and we can't set focus to it) and provokes error messages due to
::SetFocus() failures, so simply don't do this at all.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74676 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/msw/popupwin.h

@@ -25,6 +25,7 @@ public:
 
     bool Create(wxWindow *parent, int flags = wxBORDER_NONE);
 
+    virtual void SetFocus();
     virtual bool Show(bool show = true);
 
     // return the style to be used for the popup windows