As a note, I have also seen the same behaviour with wx2.8.3.
BUT it works fine with wx2.8.0.
I don't really know what's wrong. I tried to debug this and it seems it enters an infinite loop trying to get the build toolbar's combo box size.
Anyway, this might be very remotely related to wxAUI (we 're still using our bundled version of it). Just earlier I committed a related change though, so that the wxAUI from wx is used if found. Have a try with the current svn and see if this helps...