check item and wxMenu is sometimes automatic sometimes not

[olivier.corrio at gmail.com]

Hi,
when you check an wxMenuItem on wxMSW toggle is not automatic(at least
for popupmenu) but it is for wxGTK. So to resolve that i had to use a
"ugly" #ifdef __WXMSW__  because on wxMSW i got the menu event and
force the check to change its state but it is automatic on wxGTK.
Maybe it should be automatic on all plateforms.
I didn't test that on MAC so, don't know if it a "bug" or not. I m on
linux mandriva 2007 with wxGTK 2.8.0 and for windows it is also 2.8.0.
Regards Olivier