Crashes when wine desktop is active

Tried running aw-qt.exe in Wine, and to my surprise aw-watcher-window crashed when I focused the window!

Don't feel like digging up the cause right now, could be tricky.

## Reproduce

1. Open a wine desktop: `$ wine explorer /desktop=shell`
2. Hover

Eh, on second try aw-watcher-window didn't crash... wtf.