Re: IIgs "Mouse-erasing" ---- is it a virus??

[dempson@atlantis.actrix.gen.nz (David Empson)]

In article <4mm54k$2o8@gap.cco.caltech.edu>,
Nathan Mates <nathan@cco.caltech.edu> wrote:
> In article <4mln3b$4c8@lynx.unm.edu>,
> stephen e buggie <buggie@pegasus.unm.edu> wrote:
> >On some of my software, I notice that scrolling the mouse around the 
> >screen erases the portion of screen image....
> >Is this a virus or what?   Teh software continues to work.
> 
>    If this is on a Rom 3, the cause is buggy software. Apparently, the
> way things get drawn on the 3 vs the 01 changed, mostly affecting
> mouse drawing. [BeatBox is one program that suffers from this]

I don't recall this problem.  The only one I know of regarding the
mouse on the ROM 3 is that the cursor is invisible while moving the
mouse up the screen if you have a ZIP GS, and this is fixed by the
ZipFix INIT.

The problem described by Stephen is EXACTLY what happens if you have
CloseView installed, and the program isn't obeying the documented
method for locating screen memory.

CloseView tells the application to use the shadowed video buffer, but
disables shadowing and copies data to the real video buffer manually.
If the program bypasses QuickDraw and assumes the screen is always at
$E12000, then the image gets erased as the mouse moves around, because
it is being overwritten by the image starting at $012000.

If you aren't using CloseView, get rid of it.  It is in the
System.Setup folder inside the System folder.  It is installed
automatically if you use "Easy Update" to install System 6.0 or 6.0.1
on a hard drive.

(CloseView provides a movable "magnifying glass", which can be
rescaled as required.  It is intended for partially sighted users.)
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand