I've never had to do it myself (yet...) but from the accounts I've heard, IPA doesn't do too well. I definitely remember acetone being mentioned as working well (and it won't damage the glass) but you'd have to be careful not to get it on any of the electrical components I'm sure. I seem to also remember warm soapy water being mentioned, although I may be confusing this with some other adhesive that needed to be removed somewhere. There's a thread on it, I'll go fetch it up from the depths of the 68k PowerBook section.
Edit: Here ya go, it's a long read.
What did you clean the displays with before they were put on the shelf?
68kmla.org