A truly excellent toolkit. The code is very readable and the developers are quick to communicate/respond on the forum or stackoverflow.
I wish more people used it instead of writing "apps" that are just a giant web browser with javascript and a hack to get menus working correctly, with fake UI widgets that don't respond like native window controls (no proper tab navigation, no moveable or resizeable dialogs, keyboard accelerators don't work).
It's LGPL license. I wouldn't touch it with a stick when thinking about a real app.
From their ReadMe
>> wxWidgets licence is a modified version of LGPL explicitly allowing not distributing the sources of an application using the library even in the case of static linking.