About the NullWatch module
~~~~~~~~~~~~~~~~~~~~~~~~~~

If you have remote access to a RISC OS computer, or if you tend to leave your
RISC OS computed switched on for long periods of time - especially when you
are away from the computer - it can often be annoying to find that the
machine cannot be accessed or hasn't been multitasking due to things like the
following:

  * A Wimp error box is being displayed
  * A command window is open with "Press SPACE or click mouse to continue"
  * The machine has dropped to the ShellCLI (with F12)

The NullWatch module attempts to address these problems in a number of ways,
some are fairly simple and others are a little harsh so may not be required.

1) When a Wimp error box is opened, NullWatch will wait for a specified
duration (default is five seconds) before dismissing it by forcing a "Return"
keypress into the keyboard buffer. This has the effect of selecting the
default button in the error box (usually "Cancel").

If the user dismisses the error box, NullWatch will not fake any keypress.

2) NullWatch has a simple application part which periodically gets null
events from the Wimp. If it doesn't see any null events for longer than a
specified period (default is thirty seconds), it will first issue and
"Escape" key press followed by a "Return" keypress.

This is sufficient to return to the desktop from an open command window or
the ShellCLI. The escape keypress gives an alternative route out of an error
box. For example, if an application has got into a tight loop with data abort
errors, you can keep getting the error box, selecting the default button in
the error box ("Continue") may keep regenerating the error.

Pressing "Escape" will select the "Quit" button instead which may be
sufficient to recover the system into a working state.

3) If no null events have been received for a prolonged period (default is
fifteen minutes), NullWatch can take the extreme measure of performing an
OS_Reset to reboot the machine.

If you do not want this behaviour (eg. you play single-tasking games) you can
increase the timeout for (2) to some suitably large value or you can specify
a reboot timeout of zero for (3) - this will disable the reboot feature.

How to use the NullWatch module
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If you are happy with the default settings of the module, you can load it
either by double-clicking it or placing into your Boot:Choices.Boot.PreDesk
directory.

The default settings can be changed by specifying parameters to NullWatch
when you load it. An example might be:

  RMRun <Obey$Dir>.NullWatch -p 500 -c 2999 -d 500 -r 90000

where:

  -Poll <num>    = number of cs between null event for Wimp polling
  -Check <num>   = number of cs between checks that a null event has happened
  -Dismiss <num> = number of cs before dismissing a Wimp error box
  -Reboot <num>  = number of cs without null events before rebooting

The example 'NullWatch' directory can be placed into your Boot:Choices.Tasks
directory to allow NullWatch to be loaded every time you boot with your
preferred personal settings.


-- 7th software

NullWatch 0.03 (11 Nov 2004)
Copyright © 7th software, 2004
All rights reserved.