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From: mike@ai.etl.army.mil (Mike McDonnell)
Newsgroups: comp.windows.x
Subject: Problem with new widget colormap
Message-ID: <296@ai.etl.army.mil>
Date: 29 Apr 89 17:36:45 GMT
Reply-To: mike@ai.etl.army.mil. (Mike McDonnell)
Distribution: na
Organization: USAETL, Fort Belvoir, Virginia
Lines: 44

How can I change the colormap associated with a widget?  Here are some
code fragments showing attempts, with comments.

Widget w is a core widget inside a form widget. Widget w is used
to display an image.

{
  XSetWindowAttributes swattr;

  disp = XtDisplay(w);
  win = XtWindow(w);
  cmap = make_new_colormap(disp, win);  /* Works just fine. */
  XInstallColormap(disp, cmap);         /* screen flickers briefly */

  /* this works the first time and then royally screws things up!! */
/*  XSetWindowColormap(disp, DefaultRootWindow(disp), cmap); /*  */
    
  swattr.backing_store = Always; /* This works. */
  swattr.colormap = cmap;	/* This does not "take"; server resets? */
  swattr.event_mask |= (ColormapChangeMask | EnterWindowMask);
  XChangeWindowAttributes(disp, win,
			  CWBackingStore | CWColormap | CWEventMask, &swattr);
  XSetWindowColormap(disp, win, cmap);	/* This doesn't do squat. */
}

Running the >>second<< time with the colormap set to the root window gives
the following error (which I find confusing):

X Protocol error:  BadMatch, invalid parameter attributes
  Major opcode of failed request:  1 (X_CreateWindow)
  Minor opcode of failed request:  0
  Resource id in failed request:  0x8006b
  Serial number of failed request:  74
  Current serial number in output stream:  92

This error persists even when I recompile the code with the assignment
of the colormap to the root window commented out, as shown in the
code fragment above.  I have to kill the server to clear the error
condition.

HELP!
-- 
Mike McDonnell at the U.S. Army Engineer Topographic Laboratories, Bldg. 2592
Fort Belvoir, VA 22060-5546   TEL:(202)355-2716   NET: mike@ai.etl.army.mil