When the HTML/STYLES/ATTRIBUTES panel is detached, in the Attributes > Class Names field, the only way that a typed in class (or pasted in class) change takes effect is by hitting the enter key. Previously, you could just add the class and then any mouse click afterward outside the field would cause it to be applied. Same with deleting existing applied classes. I can create a video to illustrate if necessary.
When the panel is docked, the bug is not present.
Windows 7 machine. Can anyone else confirm. I have already reported this to the devs.