Capturing when button pressed event in when validate record.

 Hi All,
My requirement is as mentioned below.
I would like to restrict the user from proceeding to the next record unless he clicks on a button and enters data. This button is present in a different block.

What I am planning to do is write code in the 'When-Validate-Record'. I would be checking for a entry in that block(which opens once the 'Button' is clicked). If there is no entry then restrict user from proceeding ahead. Now the problem here is in this case form will not allow me to click on the 'Button' too.

So now I would like to know if there is any feature by which I can capture the event when the user clicks the Button. Once I get to know that the button is clicked I would be allowing the user to proceed ahead and anything other than that user will be restricted.