open the file in the current buffer,cover my origin file,maybe it should save my file before.

[wsdjeg]

    autocmd BufEnter *
                \   if empty(&buftype)
                \|      nnoremap <buffer> <C-]> :<C-u>UniteWithCursorWord -immediately tag<CR>
                \|  endif

here is my config for unite-tag,and my os is ubuntu ,gvim 7.4
then i open vim with a new file named Test.java type into

class Test{
  String
}

and do not save it,my cursor in on String then i type c-]
the vim show me the resuly in the unite buffer,if i select one and type Enter,the file will be opened in the current buffer,and cover my new file without save it!
i think it is better to confirm whether the file in current buffer has been saved,if not open the selection in a split buffer.nerdtree also has this feature ,maybe you can have a try.

[Shougo]

It is not unite-tag issue. It is unite.vim feature.

Is hidden option set? If so, you can edit the buffer and save it.
I think it is no problem.

[wsdjeg]

ok let me read the unite's doc carefully