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From: cliu@osf.org ("Chauncy Liu")
Newsgroups: comp.windows.x.motif
Subject: Re: XmUpdateDisplay fails
Message-ID: <9104081512.AA21351@osf.osf.org>
Date: 8 Apr 91 15:14:30 GMT
References: <1991Apr5.153900.22674@athena.mit.edu>
Sender: daemon@ucbvax.BERKELEY.EDU
Distribution: inet
Organization: The Internet
Lines: 51


  >  I use XmUpdateDisplay to refresh my application before starting a long
  >  load from disk and subsequent calculation.  Immediately after
  >  XmUpdateDisplay I call a routine to change the cursor, which calls
  >  XFlush; I see the cursor change, but no screen update.  What's wrong?
  >  
     I think you already received mail form David Brooks, he gave some idea how
this is happening. In the workaround, if the time to sleep is short, and the process
is huge, this will not guarantee you for a total display update before your process
begin (you have to wait till your process end then your display will be
updated totally
afterward).

  My suggestion is make a routine to update your display which guarantee display is
updated before further process

void My_Update_Display_Routine(w)
Widget w;
{
  XtAppContext app;
  Boolean BREAK = False;

  app = XtDisplayToApplicationContext(XtDisplay(w));
  XmUpdateDisplay(w);
  XClearArea(XtDisplay(w), XtWindow(w), 0, 0, 0, 0, True);
  for(;!BREAK;)
  {
    XEvent event;
    XtAppNextEvent(app, &event);
    switch(event.type)
    {
      /* Dump all the user generated events at the time of displaying */
      case KeyPress :
      case KeyRelease :
      case ButtonPress :
      case ButtonRelease :
      case MotionNotify :
        break;
      case Expose :
        if (event.xexpose.window == XtWindow(w)) BREAK = True;
      default :
        XtDispatchEvent(&event);
        break;
    }
  }
  XmUpdateDisplay(w);
  XFlush(XtDisplay(w));
}

Hope this helps
Chauncy Liu / OSF System Engineer