for my CMS (http://mediabeez.veerman.ws/mb) i have implemented transparent borders on jQuery dialogs (ui-1.6b source).
To let semi-transparent borders work properly, a fix function must be called that corrects the margins and other layout properties of the dialog .ui-resizable-n/e/s/w etc divs.
To allow easy editing of themes, i have created another function that takes a blank dialog - stripped of (almost all?) css, and applies a JSON theme-definition to it, allowing CMS builders to store (and later edit) themes in their database rather than have to write out CSS files.
If you guys (and gals?) are interested in these functions they're available for free.
I include only the fix for semi-transparent borders, coz i consider that one finished enough to share. The db-theme-apply function isn't ready for release yet, atm it uses a data-definition scheme of my cms rather than a generic one..
But i'm willing to put both in the public domain.