# Understanding FullForm in front end

I want to understand the following effect better (In Mathematica 9) .. Or, maybe, is it a bug?

Running the following line

FullForm[Subscript[α,β_]]


gives as output,

(*Output*)
Subscript[\[Alpha], Pattern[\[Beta], Blank[]]]


But then, when I try to edit the above output, I get some unexpected stuff:

There is some strange spacing at the end, and the front end disagrees with the syntax (as evidenced by the red carat).

How do I understand what's going here?

-

My guess is that since you asked for the full form, Mathematica somehow had to display α as \[Alpha] without it automatically turning into α. This is done by manipulating the underlying box forms, which you can see by inspecting the cell contents:
Probably the front end guys didn't care if the hightlighting worked fine for input cells with the nondefault option ShowSpecialCharacters->False –  Rojo Nov 1 '13 at 3:13