i've got a mapping for iterating thru suggested pop up window of omni completion
inoremap <expr> <TAB> pumvisible() ? "\<C-y>" : "\<TAB>"
but i also want a to trigger while there is no suggestions menu but a snipmate shortcut
<Plug>snipMateNextOrTrigger has been faced, but now only actual tab is inserted after an expression expected to be expanded.
inoremap <expr> <TAB> pumvisible() ? "\<C-y>" : "<c-r>=snipMate#TriggerSnippet()<cr>"