vanishing windows

[Christopher J. Hawley]

    In article <1991Apr23.190736.17417 at helios.physics.utoronto.ca>,
sysmark at physics.utoronto.ca (Mark Bartelt) writes:

|> Here's an odd bug ...
|> 
|> (1)  Open a wsh window.
|> 
|> (2)  Do something that will spew lots of text to the window
|>      ("cat -v /dev/zero" tends to work nicely).
|> 
|> (3)  Resize the window (make it tiny).
|> 
|> Sometimes, POOF!, the window disappears.  Now this is not exactly the
|> most serious IRIX bug I've come across, but I wonder whether this odd
|> behaviour is symptomatic of some more general underlying problem.
|> 
|> Configuration is 4D/25, IRIX 3.3.1, in case that matters.

    The bug seems quite readily repeatable, though I didn't learn a lot from
the experience...  ;^)  I suspect that resizing the window to dimensions
approaching zero causes an overflow or zerodivisor error when the driver tries
to figure how many lines to scroll the textport, given a line width that is
effectively zero.  (With scroll history enabled, making the window very small
leaves __no__ room for characters, just the scroll bar.)

    Output in  /usr/adm/SYSLOG  indicates the window died but doesn't say how:

Apr 24 18:05:08 sundiver grcond[13878]: CIO: wsh -fCourier.9 -m66x132 -r1000 -C056,165,059,197,080,050 -s40x80 -m66x80...

    System configuration:

	% hinv; describe
	  --------------
	1 12 MHZ IP6 Processor
	FPU: MIPS R2010A/R3010 VLSI Floating Point Chip Revision: 1.5
	CPU: MIPS R2000A/R3000 Processor Chip Revision: 1.6
	Data cache size: 8 Kbytes
	Instruction cache size: 16 Kbytes
	Main memory size: 16 Mbytes
	Integral Ethernet controller: Version 0
	Graphics board: GR1.2 Bit-plane option installed
	Integral SCSI controller 0: Version WD33C93
	Tape drive: unit 2 on SCSI controller 0: QIC 150
	Disk drive: unit 1 on SCSI controller 0

	sundiver.esd is a 16Mb IP6 running IRIX 3.3 alpha65.

|> Mark Bartelt                                             416/978-5619
|> Canadian Institute for                          mark at cita.toronto.edu
|> Theoretical Astrophysics                        mark at cita.utoronto.ca

#include	<std_disclaimer.h>
    /*  I work for SGI in a non-speaking position.  My opinins are my own. */

---
    Christopher J. Hawley / esper               chawley at sundiver.esd.sgi.com
    Silicon Graphics, Inc.    1L-945            phone:  415 / 335-1621
    Mountain View, CA   94039-7311  USA                 408 / 243-1042
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