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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: graphical output on win xp with gnavi-package
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Date: Fri, 8 Apr 2005 16:52:22 +0200
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Date: 2005-04-08T16:52:26+02:00
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On 7 Apr 2005 08:45:58 -0700, Duke Luke wrote:

> now most things are working as they're supposed to.
> i programmed a nice tetris with the gnavi package and everything is
> great.
> 
> i have only one problem left: 
> when i create a window (canvas) and paint in it, it works as long as i
> dont change its focus.
> any time i change its focus, the whole window becomes blank and
> nothing can be drawn on it further.
> => this means, one cant even click on the window to activize it,
> because that would make it blank!
> 
> why does this happen

Because Windows makes "erase background" when it wants to re-draw your
window.

> and what can i do about it?

You have to process WM_PAINT.

> do i have to use another package? which?

Perhaps, you do something wrong with gnavi. I didn't use it, so I can't
tell. It seems that neither your program nor gnavi process WM_PAINT, so
once erased window stay blank. As a guess, maybe you have told to gnavi (or
else it is always so) that your window is "owner-draw", so it does not
attempt to do anything about WM_PAINT.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de