Her editing rights ended at the movie premier. She allegedly claimed she was not aware of that until Walt told her when she was talking about re editing the movie.
Tonka, thanks for the clarification. If Travers indeed had editing rights prior to the premiere, she either wasn't involved in the production editing or for some inexplicable reason didn't invoke her rights during it - for she seemingly would never have approved the film being premiered in the form it was.
As for "Saving Mr. Banks" not including these details, that's not surprising (Disney isn't going to release a film that in any way slights its founder). But it still bothered me that the script approach taken was to fabricate a "happy-ever-after" reconcilliation that not only never happened, but which was 180 degrees away from what really transpired. This thread suggests there are a good number of people seeing the film who are taking the storyline as gospel, which it's not.