Cannot map <A-w> in insert mode in gvim?

Question

I want to map Alt+w as below, it it seems it doesn't work like other key combinations, such as which works well. What's the restriction for this key combination?

" below map doesn't work in gvim
inoremap <A-w> <C-o>w

Answer 1

If on Windows, try set winaltkeys=no

Answer 2

if alt-w opens your gvim menu, you can add this:

set guioptions-=m