NetNews Usenet Archive 1992 #20/NN_1992_20.iso/spool/comp/windows/x/16281

Text File | 1992-09-08 | 1.8 KB | 38 lines

Newsgroups: comp.windows.x
Path: sparky!uunet!usc!snorkelwacker.mit.edu!thunder.mcrcim.mcgill.edu!mouse
From: [e-mail] (der Mouse)
Subject: Re: HELP! XSetWindowAttributes and XSetWMHints
Message-ID: <[e-mail]>
Organization: McGill Research Centre for Intelligent Machines
References: <[e-mail]> <[e-mail]>
Date: Mon, 7 Sep 92 17:36:29 GMT
Lines: 28

In article <[e-mail]>, [e-mail] (Josef WIDJAJA) writes:
> In article <[e-mail]> [e-mail] (Josef WIDJAJA) writes:
>> [drawing works when, and only when, window is set override-redirect.]
> I think I now know why.  When the override_redirect is set to False,
> the Window Manager redraws the window generating an Expose event.
> Upon receving this event, the image has to be redrawn.

Yes and no.

The window manager never redraws the window.  Redrawing your window is
entirely up to you.  The Expose event always happens, and it is
generated by the server when the window is first displayed.  It's just
that when your window is override-redirect, this happens immediately
upon the window being mapped; when not, the WM makes the user position
it, delaying the actual mapping and thus the Expose.  You didn't
include enough of your program to be sure, but I suspect that you were
blindly charging ahead and drawing without waiting for the Expose.
This worked when, and only when, the window was actually mapped
immediately after your program requested that it be mapped.

That's the no part.  The yes part is that yes, you have to redraw upon
receiving Expose events, so even if the reasoning is wrong, the
conclusion is right.

                    der Mouse

                [e-mail]