Dynamic text in i/o field of dialog screen.

Hello ABAPers,

How to create dynamic text of i/o field in module pool programming after selecting date from dialog screen.

My requirement is that after selecting date from dialog screen some action should happen(some event should trigger). I am able to create dynamic text for i/o field after user interaction only(after pressing push button or enter button).

But, I want to create it as soon as user selects date from dialog screen. Please help me.