Hello,
thank you Jens for your patch.
My Internet was down today, so I did not see your patch.
I will try it tomorrow.
Anyway, I have followed your advice, and I have used the wxCustomButton: it works on Window. I have just updated the SVN - you may have a try.
I have copied the relevant code in the plugin - this way, I do not depend on wxSmithContribItems.
Have a nice evening.