Enable the channel width of an empty track to be changed (mono to stereo, etc.), and any empty track able to be changed to any other type (MIDI, Instrument, Aux, etc.). It should be doable in such a way that plugins don't change where possible. E.g., an Audio track with a set of plugins but no audio on it should be able to be turned into an Aux track with the same plugins and settings.
Idea No. 1154