Path: utzoo!attcan!uunet!samsung!zaphod.mps.ohio-state.edu!wuarchive!mit-eddie!bloom-beacon!ASC.SLB.COM!hara
From: hara@ASC.SLB.COM
Newsgroups: comp.windows.x
Subject: Re: Does XUI support dual screen?
Message-ID: <9010230144.AA11585.hara@ika.ASC.SLB.COM>
Date: 23 Oct 90 01:44:42 GMT
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 49


	 I think I find the bug in XUI code,i.e.,

	------------------- GCManager.c file --------------------	
....
static Drawable GCparents[256]; /* static initialized to zero, K&R ss 4.9 */
....

GC XtGetGC(widget, valueMask, values)
             Widget     widget;
    register XtGCMask   valueMask;
             XGCValues  *values;
{
....

    if (XtWindow(widget) == NULL) {
        /* Have to create a bogus pixmap for the GC.  Stupid X protocol. */
        if (GCparents[depth] != 0) {
            drawable = GCparents[depth];		<--- [0]
        } else {
            if (depth == DefaultDepthOfScreen(screen))
                drawable = RootWindowOfScreen(screen);
            else
                drawable = XCreatePixmap(cur->dpy, screen->root, 1, 1, depth);
           GCparents[depth] = drawable;
        }
    } else {
        drawable = XtWindow(widget);
    }
    cur->gc = XCreateGC(cur->dpy, drawable, valueMask, values);	<--- [1]

	......
	
    ----------------------------------------------------------------------

 	The program breaks at [1] with "Bad Match" error, and if you look
	at the staic variable  GCparents, it's shared if "widget" has the same 
	depth. And here is the problem, i.e., if a widget which has the 
	different root window as before (in our case "depth" is always 8) 
	is created, the same "same" drawable will be sent to XCreateGC.

	Is this already fixed? If so, can I get it? If not, I'll fix it here.

	B.T.W., the last update of our GCManager.c file was done Feb/27/'88.

	Thanks much,
	Kenzo HARA

	hara@asc.slb.com