Sorry to continue hypothesizing when the program is not open in front of me ... but to be crystal clear ...

Yes, I know that GM drums are always on midi channel 10. But I thought when a midi file was imported to BIAB it resided on the 'melody' track, which apparently also has the capacity to function as a full multichannel midi port. Or how else could this occur?

As you know a type 0 midi file all resides in a single track.

I was thinking that even though an imported midi track necessarily plays the drums on channel 10, it wouldn't show that channel 10 midi track in the piano roll or notation in BIAB ... since in a certain sense it isn't there yet.

Are you saying that any imported midi file, even though it is ... for lack of a better word ... 'hosted' on the melody track, still shows up in the BIAB piano roll or notation windows? I haven't been using the program long enough to have cemented what 'normally happens' in my mind.

BTW There is no problem with either seeing the drum track or hearing it when a BIAB song is loaded or newly created.

Prado