Does 'strut' command work in LilyPond?

[Karol Majewski]

According to:

http://www.lilypond.org/doc/v2.19/Documentation/notation/other

"\strut Create a box of the same height as the space in the current font."

So

\markup { \strut \box "." }
\markup { \strut \box "bp" }

should draw a box with constant height. But it doesn't. Maybe I'm doing 
something wrong?

-Karol