Here's a dumb GNOME Classic interface issue that I always seem to run into: desktop elements (i.e., launcher shortcuts) aren't movable or removable by the mouse alone.* Right-clicking them brings up context menus but some options remain hidden. Holding the superkey + Alt and then right-clicking makes those options show up. This forum thread was helpful.

*This may just be a change since Ubuntu 12.04. I'm just glad to have an interface other than Unity available.