Opaque is a Firefox theme that alters the opacity of buttons upon mouse hover.
One thing to note is that there is no difference between the icons used in Opaque and the default FF2 theme; the only change is the opacity. Gone are the days of having to mouseover to see fully opaque icons – with Opaque, icons are always at 100% opacity.
In terms of requirements, all you need is Firefox 2.0 or later to enjoy this theme. So, if you're looking for a way to add a bit more zest to your browsing, give Opaque a try!
Version 1.5: N/A