Comment 4 for bug 687466

Okay, I'm not sure what the package name is for the dock you're referring to, but from your description it sounds like you're running unity, so I'm reassigning the package there for diagnosis. It sounds sort of like a misbehavior in the window system functionality.

Regarding figuring out packages to file things against, yeah it's hard to determine for bugs like this. There's a page at https://wiki.ubuntu.com/Bugs/FindRightPackage that can help, but it seems to be a bit out of date. So probably best way to learn is keep filing bugs like you're doing. :-)