This is not exactly a bug, but more of a wishlist entry. The top panel/global menu bar would look nicer if it was transparent by default. I always use the compiz settings manager to set Unity's panel opacity to 0, because it really does make a big aesthetic difference to the desktop. The fully-opaque, dark-grey menu bar just looks a bit last-decade. Also, when transitioning between the new lock screen (LightDM), or when opening the Unity Dash, the way the panel suddenly switches from being dark grey to transparent is pretty jarring. That's how I feel anyway. So making the panel transparent (not *completely* transparent though, you should still see the bar going across) would not only make LightDM and Ubuntu feel more like one entity, but it would look nicer/more modern, and the transitioning between the Unity Dash and the new lock screen would look more seamless and natural as well.
Just a suggestion. Thanks. ^^
Status changed to 'Confirmed' because the bug affects multiple users.