I don't have the Theme Editor installed and probably won't muck with it as much as others seem to be when I do so I'm currently less (more?) than useless as to HOW the Theme Editor lists and names these things.
BUT...
I can only imagine the TE uses at least some kind of reference to the "official" names of the program ares.
The two areas you are pointing out are called...
1) (upper left) the "Track Inspector". There is another view that uses the same graphics called the "Clip Inspector" (just click on the "Clips" tab to the left of the "Track" tab above that bubble to see it). Based on what I've read about the TE I do not think it allows you to edit these two areas. Of course I could be wrong.
2) (bottom "black" thingie) In that image what is being point to is the "Bus Pane" background. So if you do not have enough busses to fill up whatever is visible of the "Bus Pane" that is what you see. That is the same color/premise as the "Track" and "Clip" panes in the "Track View". It's important to note that ALL of these "Panes" reside inside the "Track View" so if there is a submenu in the TE for "Track View" options that is where I would look and I would look for "Background" because that's exactly what that black bar is.
To avoid going into too much text based descriptions I will refer you to the "Getting Started" section of the Help files (online, pdf, in program, etc). There is an overall graphic of the main Sonar screen that describes the different "Panes" and other areas by name which should help a bit. Of course there are plenty of other graphics throughout the help files that will describe more in depth views like the "Track/Clip Inspector" views.
Cheers.
PS: I'd have to say the MOST useful thing I ever did when trying to wrap my head around Sonar (and other programs) was to REALLY focus on the terminology used for specific areas and tasks. It may seem screwy but by learning the "official" names for things it made searching the manual(s), forum and internet in general for answers soooooo much easier/efficient/reliable. It also helps a TON when asking questions here.