Qt Designer does not restrict slot for root window

Creating a MainWindow using Qt Designer or Qt Creator's Form Editor, then doing "go to slot" on the main window, will create a slot method with automatic naming convention.

...but this code would throw a warning during runtime that a matching signal could not be found:

QMetaObject::connectSlotsByName: No matching signal for on_MainWindow_destroyed()

Since connectSlotsByName() can only connect slots for child objects, Qt Designer should restrict automatic naming convention for the slot and generate code to manually connect the signal & slot.

Similar issue: http://ubuntuforums.org/archive/index.php/t-432590.html