I hope this is the right place to post such a question.
Yup. :)
What determines whether gvim has the top file menu or
not?
There's a 'guioptions' setting that differs between your two
environments.
Check your gvimrc on each platform. Likely, one or the
other is adding/removing the menu with something like
set guioptions-=m
to remove the menu, or
set guioptions+=m
to put the menu there.
For more information, you can read all about the gritty
details in
:help 'guioptions'
The same option controls the toolbars, scrollbars, etc.
I tend to run with them all turned off so I get as much
vertical screen realestate as possible, but some folks like
them.
-tim
PS: If you have the menu-bar on both systems, but are
*just* missing the "File" menu, something in your system
setup is seriously hosed. I'd go for a reinstall. :)
However, I presume you meant that the whole menubar was missing.