Below, the trailer for "Saving Mr. Banks," the "making of 'Mary Poppins" movie with Tom Hanks as Walt Disney and Emma Thompson as author P.L. Travers. Looks pretty good to me - obviously leaning on a fairly fictionalized version of the story (the real events didn't exactly have a cinematic arc, and neither character would come out particularly likable) but the basic idea of Walt having to realize that this isn't just one more fairytale to monetize vs. Travers possibly coming out of her own shell a bit re: the personal trauma that informed the book (Travers' father was a banker who died young, leaving her and her sisters in the care of their mentally-unwell, suicidal mother.) There doesn't appear to be anyone in the cast playing Madge Burnand, who is believed to have been Travers' partner at the time.
Unless there's a film I'm forgetting, this is the first time Walt Disney as a "real" figure has been the central character of a film, which is sort of incredible given... well, that he's Walt Disney. The Disney company put the money behind the production, but the screenplay wasn't developed in-house, it's a Black List pickup. I assume they'll probably end the film at or around the conclusion of Travers' actual collaborations with the production - Walt slightly cowed by having come up against an underestimated "children's entertainer" as headstrong as himself, Travers headed back to England having experienced some sort of self-purging catharsis - and sidestep the less-than-amicable way they ultimately split: Travers turned up at the L.A. premiere uninvited, accosted Disney at the after-party with demands to get rid of the the animated sequence (she hated cartoons) and was told matter-of-factly that "the ship has sailed;" hence why there were never any sequels even though Walt tried for them.