RobotStudio event

Robot Application Disable Close Button

Hey all,

I'm trying to disable the close button on my robot application and add my own close button within the application itself. I want to do this so i am able to ask the operator with a gtpumessagebox if he/she really wants to close the application (because doing so results in the robot system going into a controlled shutdown state and subsequently shutting down). 

The trouble i am having is not knowing how to disable the close button.

Can anyone please help.