As of now when several projects are open in tabs what's different in the Mixer is the contents, but the Mixer state and the settings are identical across all open projects simply because they're stored in reaper.ini which is global.
To illustrate, if i scroll the Mixer to a particular track in a project open in one tab, the scrolling affects tracks alignment in projects open in other tabs.
(The Mixer window state is only maintained in separate instances of the program running in parallel apparently because it's linked to the main program window. Couldn't figure out how their states are kept separate despite reaper.ini being global (RAM?). But the state still remains global when instances are closed.)
So i believe it's not unreasonable to expect the Mixer window to retain its state per project.
For example by storing it inside reaper.ini under different sections dedicated to each open project tab, having it recalled when tabs are switched, writing it into the project file when project is saved and retrieving back to reaper.ini when project is loaded.
Another thread:
Remember horizontal scroll position in the MCP
Mixer state per project?
Linear Mode
