Volume and panning controls on pattern tracks

If you prefer to split your percussion in individual BB-lines, the possibility of having better control on the song-editor BB-track offers some great opportunities.
Here in this mockup

I have added the current track-controls also on each of the BB-tracks.
That would allow me to set individual volume and stereo-position on each of the hat-variations. This is not possible now, because any volume or pan setting in BB-editor, is global for all BB-lines, this also mean that a different way to achieve the same feature, is to have individual values on different BB-lines, that would be less intuitive, but infact also give more adjustment opportunities.

Cant remember i saw this already, and i dont know if the architecture allows it (?)

Start with the song-editor BB-track controls and the BB-editor behavior described in the issue, using the linked mockup as the feature reference; no source files or tests are named. First determine whether volume and stereo-position can be stored per BB-line rather than globally, then define the implementation scope and tests needed to verify independent controls.