I read the example code of connecting signal leave with widgets ComboBox, ComboBoxText. The example calls disconnect() manually to avoid calling signal handler during ComboBox being destructed.
Does this apply to all widgets connecting to signal leave, eg. Entry, …
Signals that are emitted while an object with a signal handler is being deleted can
be a problem. See also issue gtkmm#128,
where a program crashes when a signal handler for Gtk::SpinButton::signal_value_changed()
is called during destruction.
I can’t say for sure that the leave signal will be a problem for you. If you
want to be on the safe side, I recommend that you disconnect the signal handler
in the destructor of the object with the signal handler, like in the ComboBox examples.