[Lazarus] capturing system shutdown

[Chris Jennings]

Hi All

I'm a newbie to fpc/Lazarus. I have been able to make (in my mind) 
remarkable headway in starting to develop a cross platform application 
that will hopefully end up being the begining of a major open source 
project aimed at the educational community.

I have been able to find a lot of specific information by searching 
Google and have also received a lot of quality help from members of the 
Lazarus/fpc community.

Today I have a problem that I can't find any reference to when 
searching. I need to be able to do this in both a Linux and Win environment.

1. User opens my program and begins to interact with the data behind the 
program.
2. User initiates a system shutdown or logoff without closing my program.
3. The system must transfer control to my program that will at this 
point bring up a dialog suggesting that the user save any changes and 
close the program.
4. Upon doing #3, the system then continues with shutdown or will acept 
a new shutdown command.

I know that this can be accomplished but have now idea where to start.

Any help or code segments would be much appreciated.

Thanks

Chris Jennings