sigc::signal<void>& signal_duck_selection_changed() { return signal_duck_selection_changed_; }
sigc::signal<void>& signal_strokes_changed() { return signal_strokes_changed_; }
sigc::signal<void>& signal_grid_changed() { return signal_grid_changed_; }
sigc::signal<void>& signal_duck_selection_changed() { return signal_duck_selection_changed_; }
sigc::signal<void>& signal_strokes_changed() { return signal_strokes_changed_; }
sigc::signal<void>& signal_grid_changed() { return signal_grid_changed_; }