Need info about Ada tasks

[Fionn Mac Cumhaill <invisible@hiding.from.spam>]

I've been using Ada for several years now, but I have not needed to do
anything with tasking. I have decided that I need to learn it, and
have a simple project for it, but I am finding comprehensible
information to hard to find. Cohen's book has a lot of information,
but I am finding it to be very dense reading, and a few examples would
be very useful.

What I need to do:

I am using the MingW Ada compiler and the GWindows packages on Windows
XP.

I am writing a simple program which observes a table in SQL Server
2000 and lists its rows to a visible screen display. I need a simple
task structure that can update the display periodically, with a
specified wait time between updates. I need to be able to abort the
display task at any time when the display is not being updated.

My simple solution has a minor problem; I have a select just after the
display routine that receives the abort message, but if the message
doesn't arrive on time I get another iteration of the loop before the
task aborts. How can I make this thing abort immediately, even when I
have a delay(60.0) to give a 1-minute delay between display refreshes?
I.e., how do I bail out in the middle of a delay?