Tempo map - adjustable Max and Min values

Request:
Controls for the Tempo Map to set the Minimum and Maximum tempo visible on the envelope (not affecting the tempo values possible in the song)

Benefit:
-- small tempo changes can be seen and edited more easily if the lane range is reduced
-- here is a mockup of the current and suggested feature, showing the improved (IMO) view of the tempo changes:

Reason:
-- at the moment, the envelope lane displays the full range of tempos, from 40 to 280 bpm,
-- small tempo changes of a few bpm are difficult to see,
-- small tempo changes of a few bpm are difficult using the envelope.