Doesn't focus to Gtk::Dialog buttons

[Glus Xof <gtglus gmail com>]

Hi guys,

In a method of  Gtk::Dialog derived object, I have,

// bool bt_OK, bt_APPLY....

	set_response_sensitive (Gtk::RESPONSE_OK, bt_OK);
	set_response_sensitive (Gtk::RESPONSE_APPLY, bt_APPLY);
	
	if (bt_APPLY)
		set_default_response (Gtk::RESPONSE_APPLY);
	else
		set_default_response (Gtk::RESPONSE_OK);

	gint result = run();

But at the run time, focus applies to an other child widget (the very
first Gtk::ComboBoxText...)

(I use the master, the very newest version of GTKmm 3.2.x...)

Is it possible to guess what's happen ?

Glus