I stopped counting the issues that complain about weird effects of using drupal_add_library(), specifically regarding jQuery UI.
The problem is that we auto-load the default theme of jQuery UI, which is then applied to all elements using jQuery UI's CSS classes (mostly dynamically generated DOM elements).
A quick but totally senseless fix would be to remove or comment out the stylesheet files in system_library() for jQuery UI.
I personally do not understand the jQuery UI theme API yet. However, looking at http://jqueryui.com/docs/Theming/API, I see many similarities to the CSS classes used in Drupal. Even kinda feels like re-inventing the wheel.
- Can the CSS classes, jQuery UI uses, be globally defined/altered, so we could just tell to use our class names?
- Can we implement a default theme that implements those classes, but basically is an empty/reset template only, not applying any weird styles?