how to change the back button built in event in andoird?

I'm using samsung S2 to test my tiggzi app.
when clicking on the built in back button (bottom right) i get aways to prev screen. but when at the first screen i want to bind an event that will prompt the user if he wants to leave the app.
how can i do it?

1 person has
this question
This topic is no longer open for comments or replies.