Ah, yes, if you double click on the dimension so you can move the text box without moving the rest of the dimension, you can see it behaves like the text box has fill when it is over the arrow or extension lines. It doesn't have fill if you move it over something unrelated though. Still, as far as creating dimensions, the text box might as well have fill turned on.
[image: l5C8_Screenshot-1_8_20157_20_57PM.png]
[image: mzKV_Screenshot-1_8_20157_22_18PM.png]