This is already available.
I use it all the time for my marker and chord track.
At the top of the vertical scroll bar on the right, there is a little pencil icon. The mouse over says “Divide track list”
Click it and it gives you a pinned tracks area.
If you have a pinned track selected, zooming vertically only affects the pinned tracks.
If you have a track in the area below selected, zooming vertically only affects the non-pinned tracks.
You can also adjust the height of the pinned area.