Hi,
Thats a wxWidonws question

wxGTK-2.4.2 is not ready to fully support GTK2. aMule will be compiled against wxGTK2 when wxGTK2 will be stable

As wx dev do a great job, the day will come soon.
For now, if u use gentoo, add -gtk2 in USE to compile wx and all will run fine. (as it could run fine on gentoo

)
The most important is not u use beta feature, but just have an app which do the job fine

the polish