The Ctrl-q is used in place of the Ctrl-v, since GVim on Windows has Ctrl-V mapped to the paste action. Use of the command 'ye' is essential to get the word under the cursor, in place of the command 'yw', since the 'w' will append whitespace if it can. Please note that there is an actual character in these commands, before the final . This allows for auto completion of the word under the cursor, in case there is more than one file with a similar name. Of course, the word you're wanting to use is placed in the Z buffer.

map! <F4> <Esc>b"zye:b<Space><C-r>z.<C-q>	<CR>
map <F4> b"zye:b<Space><C-r>z.<C-q>	<CR>