Off the subject slightly, roddenberry saw a longer cut of TUC just before he passed away. He hated the scene where Scotty says, "that Klingon bitch probably killed her father"
He saw the final "work print" of the film, with all elements in place. It had yet to be tweaked with a test audience. I'm not so sure it was ever made clear that
that line of Scotty's dialogue was the problem at
that particular screening - GR had already read
all drafts of the script as they were completed, and would have passed on his concerns about Federation attitudes at those times.
According to Ernie Over, GR's carer, GR's subdued reaction to the screening of ST VI in the theatrette was more along the lines of, "I'm sure the fans will love it." (He certainly didn't, as some fan commentaries insist, storm back to his office to make phone calls - he was really too ill to do much at all that week.)
Speaking of work prints, I've mentioned before that I was lucky to see a workprint of ST IV, but as this was several weeks before seeing the release version, I didn't know which "different" footage to take notes on.
The biggest differences were several storyboard sketches and "SPFX missing" slides where unfinished scenes would eventually go, and the scene of the bird of prey, doing its slingshot around the sun, had not yet been rotoscoped. Instead, a large rectangle - containing the bird of prey (on a post) and about four flannel-shirted stagehands holding smoke-filled bellows - went around the sun. It was hilarious!
There were no scrolling end credits. Instead, there was a series of faces-in-circles slides for the main cast and major guests, backed by Leonard Rosenman's music. I recall Jane Wyatt having her own slide - can't recall at what point in the list the film just ended.