Pretty much what it says on the tin—the dialogs are due for a major refactoring post-1.0. This includes adding an element to wrap the header/content/footer elements, which will cut down on back-and-forth between the dialog scripting and the DOM (adding classes to each part of the dialogs for the sake of box-shadow, for example), and will make theming more predictable overall.
More details here:
work on this is happening in the dialog-refactor branch
Landed in master,