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From: jon@UCB-VAX.ARPA (Jon Corbet)
Newsgroups: fa.info-vax
Subject: A bug in SMG
Message-ID: <8509062320.AA14457@boulder.UCBOULDER>
Date: Fri, 6-Sep-85 19:20:49 EDT
Article-I.D.: boulder.8509062320.AA14457
Posted: Fri Sep  6 19:20:49 1985
Date-Received: Sat, 7-Sep-85 14:00:13 EDT
Sender: daemon@ucbvax.ARPA
Reply-To: info-vax@ucb-vax.berkeley.edu
Organization: The ARPA Internet
Lines: 28


	I have encountered some interesting behavior from SMG, and I was
wondering if anybody else has seen this one...I have a program that essentially
wants to clear a terminal screen, so it does the following:

		smg$create_pasteboard ( --- );
		smg$create_virtual_display ( --- );
		smg$paste_virtual_display ( --- );
		smg$erase_display ( --- );
		smg$delete_virtual_display ( --- );
		smg$delete_pasteboard ( --- );

where the specific parameters have been omitted.  Now, this procedure does 
indeed clear the terminal screen, but: it leaves a channel assigned to the
terminal whose screen has just been cleared.  It seems that the call to
smg$create_pasteboard actually assigns two channels (I found all this with
a combination of DEBUG and SDA) and smg$delete_pasteboard only deassigns one
of them.
	Has anybody else seen this, and is there a way around it?  The program
of interest wants to go out and clear all terminals that are not logged in; it
becomes rather inconvenient when it retains channels to all of those terminals,
preventing them from being logged in to...

jon
---
Jonathan Corbet
National Center for Atmospheric Research, Field Observing Facility
{seismo|hplabs}!hao!boulder!jon		(Thanks to CU CS department)