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List:       kde-devel
Subject:    Re: [PATCH] Transparency support and bugfixes
From:       Timothy Whitfield <timothy () datasync ! com>
Date:       1999-02-22 19:10:30
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Thank you for the correction. I learned something.

Does anyone know how eterm does it?

Timothy

On Mon, 22 Feb 1999, Jo Dillon wrote:

> Timothy Whitfield (timothy@datasync.com) spake thusly:
> 
> > Why do we need letters? They don't look cool. ;-)
> > 
> > Ok we are about to find out exactly how much I don't know about X.
> > 
> > <IMHO>
> > It seems as if we are saying that X uses the reverse-painters algorythm as
> > far as sending rect updates, only in this case we want to use the painters
> > algorythm.  So in order to do this we have to use a non-transparent widget
> > like currently implemented in order for kwmbgnd not to paint over our
> > letters.
> > 
> > But is there any reason why we can't force kwmbknd to update before we do,
> > by sending a rect update to applications behind the window
> > with the transparency and then put the letters on?
> > 
> > Note: I did not volunteer as I am not even sure whether what I am saying
> > is possible, or just shows my ignorance about X message processing.
> >  </IMHO>
> 
>   X quite simply doesn't work this way. X has a hierarchical group of
> windows (so a button is a window inside a top-level app window) and you
> draw into those windows. If another window is over the top, it doesn't
> get drawn over. So kwmbknd /cannot/ overwrite what's in the application
> windows, since it's painting on the root window. It can't happen. No way.
> (at least, not with normal X commands - you could muck around with
> XFree's DGA extension or something, but X doesn't really provide the
> support you'd need).
> 
> -- 
> 	Jo
> 
> 

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