Is that it doesn’t pass Alt-D (or any other hotkey for that matter) to the browser. Like most developers, I use hot-keys as much as possible. It slows me down if I have to reach for the mouse all the time. And when I’m browsing I hit Alt-D a lot to get to the address bar. It’s faster for me to start typing a domain name and have Firefox autofill it rather than getting into my bookmarks.
This is just yet another way that Flash breaks the browser experience (back button anyone?).