/* prevent negative values of leftmost from creeping into tempomap
*/
- const double lower_beat = floor (_session->tempo_map().beat_at_frame (leftmost)) - 1.0;
+ const double lower_beat = floor (max (0.0, _session->tempo_map().beat_at_frame (leftmost))) - 1.0;
_session->tempo_map().get_grid (grid, max (_session->tempo_map().frame_at_beat (lower_beat), (framepos_t) 0), rightmost);
}