.vimrc

inoremap <expr> <CR> pumvisible() ? 
      \ "\<C-Y>" : delimitMate#WithinEmptyPair() ? 
      \ "\<C-R>=delimitMate#ExpandReturn()\<CR>" : "\<C-G>u\<CR>"

" <CR> accepts selected completion menu item (if it's visible) 
"inoremap <expr> <cr> pumvisible() ? "\<c-y>" : "\<c-g>u\<cr>"
" Simulate <down> button
inoremap <expr> <c-n> pumvisible() ? "\<lt>c-n>" : "\<lt>c-n>\<lt>c-r>=pumvisible() ? \"\\<lt>down>\" : \"\"\<lt>cr>"