Is visualmode() local to buffer?

[Benji Fisher]

     I checked the behavior of visualmode() while answering a question
on the vim users' list, and I noticed that the return value depends on
the current buffer.  Is this the way it is intended to work?  If so, I
think the docs should mention this.

     Example:  Open two buffers in two windows.  Use linewise Visual
mode in one and characterwise Visual mode in the other.  Try

:echo visualmode()
:wincmd w
:echo visualmode()

and one will echo "v", the other "V".

                                        --Benji Fisher