Alt+drag as raino said, plus ctrl when you release the part onto the new track if you want it at exactly the same time position.
Or ctrl+c to copy the part in the arrange window, move cursor to start of part (b or n keys with origin track selected), select destination track, ctrl+v to paste.
I tried alt+drag, but it won’t work. All the notes in the track that I have dragged to vanish and are replaced by the notes in the track that I moved. Only ctrl.Z will bring them back. I lose all the notes in the track I have dragged to.
I think raino and I are both referring to copying the midi part from the arrange page
I hold down alt and drag the string part to the spiz track, also pressing ctrl before I release it to constrain the part horizontally, so that it remains in exactly the same time position. The existing part on the spiz track doesn’t get deleted.
I alt+drag the top orange midi part onto the track below, press ctrl on release. The existing grey midi part can be seen through the copied part.
I used the glue tool to merge the two parts into one.
If I don’t glue the parts together, this is what it looks like when I expand lanes to see the 2 parts on the same midi track.
There’s nothing wrong with doing it the way you mentioned in your original post either, by copying and pasting notes from multiple parts open in the midi editor! Whatever works most efficiently for you
If I select all (ctrl A) on the selected track, all the tracks are selected on the project page. In any event, the notes are not there from one of the tracks after I open key edit.
My midi tracks cannot be overlapped by moving one track on top of another track. There is never any hatching. If a track covers another track, all the notes are lost from the covered track, with no hatching.
Perhaps you could post a few pics of what you are doing & seeing to help folks understand what is happening. Or even better an animated gif showing the entire attempt.