If a user already has there own version of jQuery UI and wants to create a custom build that includes everything but that, there will always be errors because of the hard dependence on $.ui.keyCode. A work around would be to have the user provide there own version of jQuery as well.

An example of where this sort of issue could arise, is when a user wants an updated version of jQuery UI that relies on the same vernon of jQuery that we already provide in the build.