firemonkey - Error when double-clicking TButton in FMX form application at design-time -

in delphi xe8 (update 1), choose file > new > multi-device application - delphi > blank application.

then put tbutton on form.

then double-click button. automatically create empty click event-handler declaration , implementation (like vcl form application projects):

procedure tform1.button1click(sender: tobject); begin  end; 

however, display error message:

so why error message displayed? bug in ide? can prevent error?