It would be really handy to have the master volume ALWAYS available - whether in split view or single view - and locked on left or right of screen.
In rigs where there is no “big knob” volume control to hand - this can be really essential for quickly turning down unexpected blasts of sound.
In fact might be good to also be able to "lock other levels to one side at all times - for example CUE volume.
These faders would then be visible at all times with the rest of the screen changing as needs demand.
perhaps graphics/colour could also make the MASTER a bit more obvious.