This is a strange phenomenon. When I start out a brand new document the viewport tabs all look like this: 
I work for however long and then save and exit. When I open it back up after a week the tabs are rearranged for some reason like this:
I don’t ever change them, I think they have become sentient and change themselves…
How do I lock these things into place?
And also, my ‘move’ option is greyed out:
Hi Jake, I’ll check on the ordering, thanks for pointing that out. The Move/Copy is for layouts, which appear as new tabs.
-Pascal
So, for now it is not possible to move the viewport tabs?
As of now, I think that’s correct. We aren’t able to drag them around to
change order.
I’ve resorted to just changing each individual tab until I like the
ordering.
Hi all, apologies for resurrecting this ancient thread, but this issue appears to still be present in Rhino 7.31. @pascal do you have any news on the topic? It is very annoying to have viewports sorted by ascending order, for example, only for them to get scrambled each time the file is saved.