How to bind <lwindow>-; with a function on windows?

[anhnmncb]

When I type M-x global-set-key RET, then press <lwindow>, the help
window pops up and show:

<rwindow> runs the command ignore, which is an interactive compiled
Lisp function in `subr.el'.

It is bound to <mouse-movement>, <language-change>, <lwindow>,
<rwindow>.

I have no chance to press <lwindow>-; to function. Type them in emacs
window just produce a ;.