I am using oracle forms 11g. i have windows in my form, when i click on top right corner (x) button to close, the form does not get close.
i have set its property model=yes and hide on exit=yes
Use a WHEN-WINDOW-CLOSE-trigger to close the window.
At the Form level create a trigger "WHEN-WINDOW-CLOSED" and in that write "EXIT_FORM" which will close the window when you click on the 'x' button on the window.
Hope it work for you, working fine for me.