The NetScaler themes in 12.0 look to be buggy. I implemented a Office365/ADFS combo. When adding an account in Word (or another office app) normally a resized window opened and the NetScaler presents a login page (screenshot 1) . When upgrading to NetScaler 12.0 I get a lot of scripting error and a blank page, unable to add an Office365 account (other screenshots).
I now have 1 node 11.1, 1 node 12.0 - failing back to 11.1 and it immediately starts working again. Failing over to 12.0 and it's broken again. Clearing out caching groups doesn't solve. Maybe I'm overlooking something. It happens with all the themes.