create app that reads and reacts to messages...

I looked around but can't find anything close to this. I can create most of the app but I don't know how to do the parts as follows.
A - read a message that gets put on the windows screen.
B - react to it i.e. button or mouse click.

We are trying to take a function away from Pandora that stops the transmission after X amount of minutes and puts a message screen on windows to see if you are still listening. We use this in our chat "office" and would be good if we did not need to worry about it and could move on with this. I have been thru the API's and don't see what I think would be that "listener". Could really use the help.