Re: Display & Actions

Alan Freed (al@sarah.lerc.nasa.gov)
Tue, 4 Jun 1996 13:09:50 -0400 (EDT)

Guy wrote:

>I've encountered a screen-update problem which causes TextView windows to
>get completely scrambled after scrolling them. To reproduce it consistently I
>perform the following:
>
>a. Open TextView window in browse mode (say the 'Users Guide')
>b. Position the new window so its bottom edge is 'below' the bottom of the
>'main' Oberon/F window. Something like:
>
>---------------------------------
>| | <-- the main Oberon/F application window
>| |
>| |---------------| |
>| | | <-- A TextView window
>| | | |
>| | | |
>| | | |
>---------------------------------
> | |
> | | <-- This part of the window isnt visible
> -----------------
>
>
>c. Repetitively scroll downwards using the 'down' arrow key. When I scroll
>downwards _slowly_, the bug doesnt appear, but if I press and hold down the
>key so that it auto-repeats the bug consistently appears with all TextView
>windows that I've tried. The speed of the scrolling is important, so
>if you cant reproduce the problem, perhaps try to increase the 'repeat rate'
>in the Keyboard section of the Windows Control-Panel.
>
>This is with Oberon/F V1.2 (educational version) on a PC running Windows 3.11.
>I have an ATI mach32 display adaptor - the bug may be with the driver,
>though I dont think so because I havent had any similar problems in the last
>year or so of using the adaptor.

I'm using the educational version (until shipment of the developers version)
of Oberon/F V1.2, also, but I'm running under Windows NT 3.51 with Service
Pack IV installed (FYI, NT Service Pack III has a nasty bug in WinServ.dll).
I do not experience the problem you speak of.

I've got a question relating to Services; in particular, the use of Actions
exported from module Services. Two examples are given in Obx on how to use
these, but I'm having problems getting them to work in my application. Has
anyone else tried using Actions, and if you have, have you experienced
difficulties?

My application is for numerical integration. I've written a package, Ode,
that integrates ordinary differential equations. In the base module,
Integrators, resides a local procedure called Step which handles an
integration step. This is called repeatedly in any given integration
analysis, and as such, is a logical candidate to construct an Action
around. I've tried six to ten different ways of constructing an Action -
none worked.

What I seek to find is anyone who has successfully written an Action call,
and then discuss the problem with them in more detail. After that, I'll
contact Oberon microsystems for further input, hopefully better informed
than I am at present.

Al Freed