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From: RWS@ZERMATT.LCS.MIT.EDU (Robert Scheifler)
Newsgroups: comp.windows.x
Subject: Why can't I inquire about borders?
Message-ID: <871030091519.3.RWS@KILLINGTON.LCS.MIT.EDU>
Date: Fri, 30-Oct-87 09:15:00 EST
Article-I.D.: KILLINGT.871030091519.3.RWS
Posted: Fri Oct 30 09:15:00 1987
Date-Received: Wed, 4-Nov-87 21:29:44 EST
References: <2771538053-221473@Sierra>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 23

One of those perennial questions, I suppose.  Consider the following:

	(let ((pixmap (xlib:create-pixmap :drawable w :width 10 :height 10
					  :depth (xlib:drawable-depth w))))
	  (setf (xlib:window-border some-window) pixmap)
	  (xlib:free-pixmap pixmap))

For those who can't read it, suppose you create a pixmap, store it as a
border pixmap, and then free the pixmap. [Doesn't it irk you when people
speak in foreign tongues?]

This is legal according to the protocol (and, if you have no further
need to reference the pixmap, is a fine idea, since the server may be
cleverer than you at finding alternate implementations of what you ask
for).  When you free certain resources, like pixmaps and cursors, what
is freed is the association between the resource id and the object; the
object itself is not freed until all internal references within the
server are gone (reference counting is typically employed in the absence
of automatic garbage collection).  So, when you free the pixmap, the
border of the window remains unchanged, but there is no longer an
external name to be handed out to clients that might ask for it.  Since
resource-id allocation is controlled by clients, there is no
particularly good way for the server to create one on the fly.