Worked: Probably never
Short description of error
OK, this confused me when I tried making my first theme. For properties, "Title" changes the same thing as "Region Text Titles" for the other editors. If this isn't a bug, it sure is weird and confusing when making a theme.
Also, I just noticed today(5/26/2018). "Region Text Titles" for the movie clip editor, also changes the image editor setting. If you change the region text titles for the image editor, it doesn't do anything.
Exact steps for others to reproduce the error
Screenshots should be enough.