public void destroyed (ref unowned Widget widget_pointer)
This function sets *
widget_pointer to null if
It’s intended to be used as a callback connected to the “destroy” signal of a widget. You connect destroyed as a signal handler, and pass the address of your widget variable as user data. Then when the widget is destroyed, the variable will be set to null. Useful for example to avoid multiple copies of the same dialog.
address of a variable that contains this