b->signal_clicked().connect (
sigc::bind (
sigc::mem_fun (*this, &ExportTimespanSelector::set_selection_state_of_all_timespans), true
)
);
option_hbox.pack_start (*b, false, false, 6);
b->signal_clicked().connect (
sigc::bind (
sigc::mem_fun (*this, &ExportTimespanSelector::set_selection_state_of_all_timespans), true
)
);
option_hbox.pack_start (*b, false, false, 6);