Songtrix

Not really possible at this stage, and probably confusing.

If you really mean editing more than one BAR (measure) at a time, this can be done easily by joining segments.

A segment is a very flexible thing, it can be a single bar (this is the default with rhythm and drums segments as it is convenient to repeat them) or the whole track (as with melodic tracks), or anything in between.

If I understand correctly, you probably want to have a rhythm or drum segment of many bars?  This is easy.

Select the range of bars you want to join (or select a single cell in the track  and use Edit-Select-Tracks to select the whole track) then use Segment-Join to turn all of the single-bar segments into one multiple-bar segment.