#468 Minimizing and maximizing app with 'Prefs' window open

[had9]

hi,

to bug reproduce, follow below steps:

1.) clean install of smplayer
2.) open a file to play (audio or video doesn't matter)
3.) now open the 'Preferences' window
4.) now minimize the application
5.) now maximize the application
6.) notice brief 'flciker' of SMPlayer's video interface over the maximized prefs window

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Windows 7 sp1, SMPlayer 0.610 -portable
mplayer:
video driver: direct3d
audio driver: win32 audio driver