I want to roll both 9.1 and Citrix 6 out as soon as I can. I have the same problem with Citrix 6.0 Client running 9.1. No fix is currently available and no word from Citrix. I too have see the problem where the Citrix client highlights all text as black and therefore unreadable. Reverting to Client 4.1 solves the problem with minimal impact to my daily work - your mileage may vary and the 4.1 client may have bugs that the 6.x resolved.
Menus seem to act like a big eraser.
Considering Citrix probably has one guy in the broom closet with a Mac IIci who's writing the client, the likelihood of this getting fixed soon is pretty slim. They must've just gotten him a 6100, though, since the new client allows for multiple apps to run at once. Look at their manuals. They show System 7 screen shots. For instance, if you have your Mac set to Millions Of Colors, and the ICAClient to 256 colors, it will have redraw problems.