[plt-scheme] Keyword menge\

I defined function menge\ and I want to make
it specially indented begin like keyword
(preferences->editing->indenting) but I'm failing.
I know I have to add it in the form menge\\ and then
it really occurs as menge\ in list of keywords,
but it is still black instead of dark red like other
keywords. Unlike this, other similar function, menge\!
is accepted well.

Is it some (small) bug or I'm doing something wrong?

Thank you,
Kazimir Majorinc