emscripten how to prevent browser's hotkeys from taking over.

[qunying]

With the given simple locktest example. locktest.tar.gz

After loaded, under firefox, if press "alt+d", focus goes to url bar, alt+e goes to edit menu, etc. Under chrome, if press "alt+d", focus goes to url bar,m "alt+e" goes to menu. Is that possible to prevent browser from interpreting any of the keystroke in the emscripten window?

I try to use SDL_SetWindowKeyboardGrab90, but it seems has no effect.