Gecko plugin peer here: Unfortunately, no. NPAPI has two modes: windowed and windowless. In windowless mode (roughly): we proxy input to flash, and flash renders into a buffer we provide it. In windowed mode, we create a native OS child window for flash and let it handle input and rendering directly. In this mode, without a way for flash to pass "unused" keys back to us, it will require some ugly hacks to steal hotkeys from it reliably.

Most sites run flash in windowed mode, and for good reason - flash's performance sucks in windowless mode, and it cannot make use of hardware acceleration (IIRC). Since Adobe's NPAPI flash seems to be essentially in stability mode, it's unlikely this will be improved :(

Now, in current multiprocess mode, we actually force flash to use windowless mode -- because support for windowed mode isn't finished yet (bug 923746). But the aforementioned performance issues mean that we'll probably remove that restriction once we support windowed mode in multiprocess.

No.