[winswitch] current using window is on top

[Long Nguyen Thanh]

Hi,

After use xpra about 30 minutes -> 1 hour. Bellow bug appear:
Reproduce:
1. Start xpra : xpra start :100 --start-child=xterm --bind-tcp=0.0.0.0:10000
2. Attach xpra: xpra attach tcp:IP:10000
3. Use some apps : firefox, chrome,...
4. Bug:
 Current using window is on top with other windows.
 Use "raise windows" under tray icon menu and it's ok.

I attached the bug report.