add: break;
context: button_press_event (GtkWidget *widget, GdkEventButton *event){    gerbv_zoom_data_t data;    gboolean do_zoom = FALSE;    switch (event->button) {    case 1 :	if((event->state & GDK_SHIFT_MASK) == 0) {	    /* Plain panning */	    screen.state = MOVE;	    screen.last_x = widget->allocation.height - event->x;	    screen.last_y = widget->allocation.width  - event->y;	} else {	    GdkCursor *cursor;	    screen.state = MEASURE;	    screen.start_x = event->x;	    screen.start_y = event->y;	    cursor = gdk_cursor_new(GDK_CROSSHAIR);	    gdk_window_set_cursor(gtk_widget_get_parent_window(widget),				  cursor);	    gdk_cursor_destroy(cursor);	    	}	break;    case 2 :	/* And now, some Veribest-like mouse commands for	   all us who dislike scroll wheels ;) */	do_zoom = TRUE;	if((event->state & GDK_SHIFT_MASK) != 0) {	    /* Middle button + shift == zoom in */	    data.z_dir = ZOOM_IN_CMOUSE;	} else {	    /* Only middle button == zoom out */	    data.z_dir = ZOOM_OUT_CMOUSE;	}	break;    case 3 :	/* Zoom outline mode initiated */	screen.state = ZOOM_OUTLINE;	screen.start_x = event->x;	screen.start_y = event->y;	screen.centered_outline_zoom = event->state & GDK_SHIFT_MASK;	break;    case 4 :	data.z_dir = ZOOM_IN_CMOUSE;	do_zoom = TRUE;	break;    case 5 : 	data.z_dir = ZOOM_OUT_CMOUSE;	do_zoom = TRUE;	break;    default:    }    if (do_zoom) {	data.z_event = event;	zoom(widget, &data);    }    return TRUE;} /* button_press_event */