Just tried 15.34. Its still the same.
I did however discover a way to avoid freezing. I did submit the info to the bug tracker, hope that helps.

Way to avoid freezing: (only tested with 15.34)
Open MUI prefs (I always do a reboot before testing, so I can reproduce results easier)
Then go straight to the About window, press the show button and browse through the classes list.
Then close the About window.
Go to TextEditor and start moving that cursed slider again -- No freezes.

I'd be happy to know if the same applies to the others confirming this bug earlier.