To reduce the number of possibilities, I load Tungsten into the theme editor and look at only the modified entries. The filters are on the theme editor view tab.
Sometimes you can get lucky by searching for the name. This works in the case of the "Add Track" buttons especially when looking at only modified entries. There are two "Add Track button" images in the
Track View > Add Track Flyout.
The track control list drop is a little harder to find. I looked at modified images with more than 2 states in the Track view. I knew it was an image with more than 2 states because the menu changes color when the mouse hovers over it. I found it in
Track View > Track Pane and it goes by the unfortunate name of "Edit Filter."