Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!ZERMATT.LCS.MIT.EDU!RWS
From: RWS@ZERMATT.LCS.MIT.EDU (Robert Scheifler)
Newsgroups: comp.windows.x
Subject: Re: GXxor
Message-ID: <19880608115801.8.RWS@KILLINGTON.LCS.MIT.EDU>
Date: 8 Jun 88 11:58:00 GMT
References: <8806080059.AA00216@kitt1.ws.sony.junet>
Sender: daemon@bloom-beacon.MIT.EDU
Organization: The Internet
Lines: 18


    Date: Wed, 08 Jun 88 09:59:04 +0900
    From: kddlab!ws.sony.junet!michael@uunet.uu.net (Michael Knight)

    Our Xserver is that WhitePixel equal 1 and BlackPixel equal 0.
    I can't see rubber band in window.

    So, I changed GXxor to GXinvert in main.c at line 233.

This is a common mistake in X programming.  If you have two values
(pixelA, pixelB) that you want to swap between, you should either:

    set the GC foreground to (pixelA ^ pixelB) and function to GXxor
or
    set the GC planemask to (pixelA ^ pixelB) and function to GXinvert

Otherwise, your code will fail on some sex of monochrome display or some
variation of color.