In truth, I don’t know
My thinking was that since the RMB is normally used (in most applications) to pop up context menus relevant to the position they are clicked, and I am re-assigning the RMB, and freeing up the MMB, I would swap the “context menu trigger” to the MMB.
But whilst the RMB brings up context menus most places, it doesn’t seem to do so in the main window, so perhaps its not necessary there.
Or, maybe it did before I reassigned RMB?
Truth is, I paranoid about changing anything now I seem to have something I find usable in case I screw it all up again.
For example: I thought that I would remove the “scene” menu on the right, as I am not using it, so I clicked on the diagonal lines (as I saw in one of the videos and attempted to drag it away. Instead, it gave birth to a copy, and when I tried to drag that back again, it birthed another. I tried right clicking in various places, but the doesn’t seem to be a “remove this pane” option anywhere.
So (again) quit out and restart and hope that it doesn’t remember my c***-ups.