Path: utzoo!attcan!uunet!ginosko!usc!bloom-beacon!EXPO.LCS.MIT.EDU!rws
From: rws@EXPO.LCS.MIT.EDU
Newsgroups: comp.windows.x
Subject: Re: XCopyPlane confusion
Message-ID: <8908221249.AA05884@expire.lcs.mit.edu>
Date: 22 Aug 89 12:49:01 GMT
References: <8908212228.AA25502@Athens.local>
Sender: daemon@bloom-beacon.MIT.EDU
Organization: The Internet
Lines: 6


    When I call XCopyPlane, using 'a' as the source and 'b' as the
    destination, the call fails with a BadMatch error.

Probably the depth of the GC you are passing doesn't match the depth of 'b'.
This is also a (documented) condition for BadMatch.