... at least give the option to unlink the mixer from the main window so I can have a static mixer window that is not affected by selecting tracks in the main window.
The usage case is when you want to view auxes in a mixer window e.g. yoru sub groups/stems and FX returns, and then you go an select a software instrument track in the main window, then the mixer window with the auxes jumps to the software instrument "aux" track and you lose your view.
An option to unlink is a basic necessity.
The option to "lock" a mixer view (any/all mixer windows) so that it is saved with a screenset would be even better.
The most advanced option would be to be able drag/drop channels in the mixer window and then be able to lock/save the mixer window view (e.g. save a mixer view preset/patch not unlike a lane set etc.)
...But just please give the option to unlink!