For instance, a shortcut to select the volume column only. Another one to select just the delay column, etc. I use those two masks A LOT and it would save me both time and wrist pain if I didn't have to use the mouse every time I need them.
Apparently, since 2011 this property has been requested to be observable, not read only:
-- The currently edited sub column type within the selected note/effect column. renoise.song().selected_sub_column_type -> [read-only, enum = SUB_COLUMN] renoise.Song.SUB_COLUMN_NOTE renoise.Song.SUB_COLUMN_INSTRUMENT renoise.Song.SUB_COLUMN_VOLUME renoise.Song.SUB_COLUMN_PANNING renoise.Song.SUB_COLUMN_DELAY renoise.Song.SUB_COLUMN_SAMPLE_EFFECT_NUMBER renoise.Song.SUB_COLUMN_SAMPLE_EFFECT_AMOUNT renoise.Song.SUB_COLUMN_EFFECT_NUMBER renoise.Song.SUB_COLUMN_EFFECT_AMOUNT
If renoise.song().selected_sub_column_type were accessible, it would be very simple in a tool to direct the cursor in a specific sub-column, and therefore, assign a specific keyboard command.