Newsgroups: comp.windows.x
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From: mouse@lightning.mcrcim.mcgill.EDU (der Mouse)
Subject: Re:  oxymoron question: outputing to InputOnly window
Message-ID: <9105152349.AA04899@lightning.McRCIM.McGill.EDU>
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Date: 15 May 91 23:49:45 GMT
Lines: 33

> I know this sounds crazy, but is there any way of outputing something
> (like drawing text) to an InputOnly window?

No.

> What I want to be able to do is draw some stuff on a "transparent"
> window.

Ah.  This is a relatively common request.

What everybody seems to want is a window that is either transparent
(catches events but lets what's behind it show through, even when the
stuff in back changes) or nonexistent (neither obscures stuff behind
nor catches events), except where something has been drawn on it.

Standard X does not provide anything of the sort.  The closest
suggestion I can make is to use the SHAPE extension to shape the window
to fit the graphics.  (This gives the second alternative I mentioned
above, nonexistence.  To get transparency, conver it with an InputOnly
window and diddle your event handling.)  Unfortunately, changing shapes
is typically very slow, so this is practical only when you're doing
something whose shape doesn't change often.  (Also, if your application
may have to run on servers that are old enough to lack SHAPE, it
naturally can't work.)

The next closest suggestion is to use a window with background None.
This has the disadvantage of not letting changes to the windows
underneath show through.

					der Mouse

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