I create main SDI form of my app. I want avoid of user to immediately closing main form clicking on close button on upper-right corner of form. I add to destroy event of form next few lines.

if messagebox('Do you really quit application?',36)=1
clear events
else
return .f.
endif

If user answer Yes, form close. It is o.k. If user answer No, form close too. How can I prevent closing form, if some condition is not meet.

Maros Klempa