App Designer - How to create a callback function for pressing the 'Close Window' Button

Hello,

I would like to give the user a warning when certain actions have not been done, such as selecting a number of options from dropdown lists, and the user attempts to close the window by pressing on the 'x' shown below.

How can I create a callback function for this button?

Thanks,

Carlos

Answer 1

[Mario Malic]

Hi Carlos,

here's the answer from Adam Danz.

[Carlos Acasuso]

Thanks Mario, that is very useful.