I was going to possibly make a request for something like this but my requests have not been too successful.
This might be a tricky thing to add.
I was wondering if anyone knows if this is already possible, or have any tricks for achieving the following.
In other DAWs I have seen this called “ghost notes” but basically it is being able to see another tracks MIDI notes in the background in Piano Roll of currently active MIDI track.
Only thing I have been able to think of is just copying the other MIDI region into current MIDI track, but not that good.
At one time I thought I did something like muted the MIDI region to gray it out but that does not work for me right now.
Also I like to show note velocity inside MIDI notes but can be confusing when both regions are showing them.
Anyways, if anyone has any ideas to mimic this behavior, please let me know
Just guessing, but what you are asking for sounds like it is related to the work on the Pianorule branch mentioned by @paulhere. AFAICT, that work is still ongoing (see the branch on Github), but has no definite timeframe for delivery to a released version of Ardour.
ghost track colors are used when drawing a MIDI region behind MIDI CC (automation) data. It’s a “ghost” because although you can see it, you cannot interact with it.