> you mean gvim?  does vim do tabs somehow then?

I don't use GVim because it doesn't work inside screen, but yes, Vim
and GVim both do tabs.  Try `:help tab-page-intro` to get an overview.

The basic commands are:

:tabnew -> open a new tab
:tabedit index.rhtml (or :tabe index.rhtml) -> open file index.rhtml
in a new tab
:tabclose (or :tabc) -> close current tab
:tabmove 4 (or :tabm 4) -> move current tab after tab 4

gt (or :tabnext) -> next tab
gT (or :tabprevious) -> previous tab
4gt -> go to tab 4

The excellent and indispensable rails.vim plugin has some nice tab
support features.

I'm not sure if OS X Vim has tab support by default...