I'm aware of that Style Properties page; however unless I'm mistaken, it modifies the control only when mouse is hovering over it. In other words, this is the control's hover state. I'm asking how I would go about modifying the hover state of other elements, which would alter the control's appearance.
I'm not sure what elements it is you're trying to change - your original post stated "How do we alter the hover state of message controls (e.g. "Like", "Edit")" but now you want the user name?
Which elements exactly are you trying to change?
What do you want them to do?
Interesting, now that I think about it, the RSS-feed buttons in the main forum_list behave exactly the same way, "on" only when the mouse hovers over that section of the forum.
There's got to be a simple way to replicate that here...