Windows 10 64b
Broken: 2.79, Tried also on 2.8 26ee700
Worked: I think it never worked. I am not sure
Short description of error
You can change multiple number by click and drag down and than write number you want for all selected fields. It works also for all transforms in N panel in 3D view (i forgot ist name) expect for dimensions. It will just stay whatever it was before.
FYI: i tried on text for X and Y and it set Y dimension same as X one was. Not what wrote.
Exact steps for others to reproduce the error
-Open defauld scene.
-select multiple "2" in dimension and write something else.
-after confirmation nothing will change.