Hello Yustas,
I'm not sure which action are you going to handle to the mouse click. Anyway I suggest to you to take a look to this function:
EventCellClick for XTable
This would trigger in user dialog boxes when a cell in an extended table is clicked. I figured out that's is the closest solution to you question.
Let me know if you need additional help.
Have a nice day!
Related Links:
Using Dialog Boxes in DIAdem
Matteo
