New wx patch

Hi Dave,

I nailed down and fixed another clipboard bug. Actually, it's the same
problem we had with gtk, so I extended an existing patch.
I uploaded a cumulative patch to snake, but for compiling a new wx
snapshot you'd probable be better off if you apply the attached patch
separately. Since three files in the current snapshot are already
patched, the re-patch probably fails. Just get a fresh copy from wx cvs,
or I could mail you the files if you like that better.

For gtk, nightly builds do *not* need this additional patch, because the
new patch is just a reimplementation; this change affects only msw.

Regards,
Andreas