Outlandish graphics functionality sought?

["RDP@ALAN.LAAC-AI.Dialnet.Symbolics.COM" <"RDP%ALAN.LAAC-AI.Dialnet.Symbolics.COM %ALAN.KAHUNA.DECNET.LOCKHEED.COM"@WARBUCKS.AI.SRI.COM>]

Date: Thu, 27 Jul 89 10:27 PDT
From: Robert D. Pfeiffer <RDP@ALAN.LAAC-AI.Dialnet.Symbolics.COM>
Subject: Outlandish graphics functionality sought?
To: SLUG@ALAN.LAAC-AI.Dialnet.Symbolics.COM
In-Reply-To: Your message of 26 Jul 89 17:15 PDT
Message-ID: <19890727172746.2.RDP@ALAN.LAAC-AI.Dialnet.Symbolics.COM>
 
    Date: Wed, 26 Jul 89 16:07 PDT
    From: barmar@THINK.COM
 
	Date: Wed, 26 Jul 89 15:34 PDT
	From: Robert D. Pfeiffer <RDP@ALAN.LAAC-AI.Dialnet.Symbolics.COM>
 
	I'd like to be able to draw lines and arrows where the first endpoint's
	coordinates are specified relative to one window pane, and the second
	endpoint's coordinates are specified relative to another window pane.
 
    What you need to do is find a common ancestor of the two windows (if they're both panes of the
    same frame, then this is simply either one's :SUPERIOR), convert pane-relative coordinates to
    ancestor-relative coordinates, and then draw the arrow in the ancestor.  There are messages to
    windows that will tell you the offset of the window's top-left corner in its superior, so you
    can use this to compute the offset you need to apply to pane-relative coordinates (if you have
    to go back several window generations to find the common ancestor then you'll have to sum these
    offsets).
 
Why, yes, I think that will do the trick.  Unless anyone else on the
list sees a reason why this wouldn't be the Right Thing to do, I think
I'm sold.  Thanks, Barry.