gistfile1.txt

function! ToggleXHTML()
    if &ft != 'xhtml'
        let s:oldFileType = &ft
        set ft=xhtml
    else
        if exists('s:oldFileType')
            let &ft=s:oldFileType
        else
            echo "No previous filetype"
        endif
    endif
endfunction

command! ToggleXHTML call ToggleXHTML()
map <silent><Leader>h :call ToggleXHTML()<CR>