Got a nice e-mail from a reader regarding last month's comparative review of the 1924 and 1940 versions of The Thief of Bagdad, pointing out that I'd been rather mistaken about the setup of the 1940 version: unlike in the 1924 version, in which Douglas Fairbanks is both the Thief himself and the romantic lead, in the 1940 version Sabu is in fact the titular thief, and John Jason, the romantic lead (who appears to have been cast largely on his resemblance to Fairbanks) is the deposed Caliph of Baghdad, and so the story is, in fact, one in which the Thief, through his skills, helps the deposed Caliph to win the princess and the throne, making the apparent "sidekick" the hero and vice versa (to explain, my viewing was interrupted a few times-- as I've implied below, I was watching it on More4 while working from home).
I'm still not sure that this makes it a better story, in my eyes, and to my mind splitting the Fairbanks character into two confuses the issue: rather than having a single character undergo trials and receive the traditional fairytale reward of the princess' hand in marriage, riches and a kingdom, you have the effective "hero" undergoing most of the trials but at least two-thirds of the reward going to someone else (q.v. Ivanhoe: Rebecca does all the work, nurses the hero back to health, and braves the Normans with him, but bloody Rowena, who does nothing at all in comparison, is the one who winds up marrying him). It also turns the romantic subplot into something shoehorned in to provide a conventional narrative, rather than the point of the film, and means that the narrative kind of flops back and forth between the romance and the real story-- a bit like those Marx Brothers movies in which the studio has insisted on some kind of conventional dramatic narrative, but it's quite plain that what the film really wants to do is chuck the detective/young lovers/whatever and focus entirely on Groucho, Harpo and Chico.
My correspondant made a good point that having Sabu as the titular character does make the film enjoyable for children, in that it's the young protagonist who saves the day and does all the fun stuff like stealing the idol's eye and fighting the giant spider, which is a good point (and I do have to say that I think Sabu is due a bit of a revival really)-- but personally, from the point of view of an admitted film snob and silent buff, I still prefer the original.