Editor Tool Highlight Usability Problem
In the new discussion & reply editor, every tool in the toolbar highlights whenever the pointer is placed over it. This is not desirable because several tools that toggle features on & off also use the same highlighting to indicate their on or off status.
The problem with this is that if one turns on or off a toggling tool, there is no indication that its status has changed until the pointer is moved off the tool.
For example, if the spellchecker is turned on & I want to turn it off, clicking the tool gives me no immediate indication that I have done so. And since there is a brief (& sometimes not so brief) delay before the editor window shows the change, I might be tempted to click the tool again because I thought the first click was not recognized. The result is I have toggled the tool off & then back on again, so it seems as if the tool won't turn off.
The same problem can occur with the text style tools, for instance when trying to remove bolding from a highlighted word or phrase.
There are several solutions for this but I think the simplest & most intuitive is simply not to have the tools highlight when the pointer is over them. To indicate that they perform actions, the pointer could change from an arrow icon to the pointing finger one, just like they do elsewhere in the UI for things like the "Your Stuff" item at the top of the page. Highlighting should be reserved for status indication.