I can expand a vertical split screen to occupy most of the area using Ctrl+w+|Now I would like to map that shortcut to Ctrl+m. I tried the following but it failed. nnoremap <C-m>    <C-W>|However this does not seem to work I also triednnoremap <C-m>    <C-W-l>However that fails also. Any suggestions?
Assign shortcut to a Split window resize Ctrl+w+|
key bindings;macvim;split
| is the command separator, so it terminates the map. You need to escape it:nnoremap <c-m> <c-w>\|Or use <bar>:nnoremap <c-m> <c-w><bar>See :help :bar and :help map_bar.