void clear_selection_except (ArdourCanvas::CanvasNoteEvent* ev, bool signal = true);
void clear_selection (bool signal = true) { clear_selection_except (0, signal); }
void update_drag_selection (double last_x, double x, double last_y, double y, bool extend);
void clear_selection_except (ArdourCanvas::CanvasNoteEvent* ev, bool signal = true);
void clear_selection (bool signal = true) { clear_selection_except (0, signal); }
void update_drag_selection (double last_x, double x, double last_y, double y, bool extend);