#70 qGo2: program still running after all windows closed

[yzhh]

As the title says - I thought the program is closed since there was no window or systray icon left for it. But at a later time a game challenge came out (someone want a game with me).

I can't reproduce the bug. But I think it might be related to a unfinished game with gnugo (a game that goes to end of selecting dead stones, but not 'done' since the user can't click that button).