+ case GDK_SCROLL_LEFT:
+ xdelta = (current_page_frames() / 2);
+ if (leftmost_frame > xdelta) {
+ reset_x_origin (leftmost_frame - xdelta);
+ } else {
+ reset_x_origin (0);
+ }
+ break;
+
+ case GDK_SCROLL_RIGHT:
+ xdelta = (current_page_frames() / 2);
+ if (max_frames - xdelta > leftmost_frame) {
+ reset_x_origin (leftmost_frame + xdelta);
+ } else {
+ reset_x_origin (max_frames - current_page_frames());
+ }
+ break;
+