I do admit that I don't follow all of this thread. Keystrokes are sent to an active window (has focus) in any OS, even if it happens to be the desktop. If you need to use a keystroke in your host OS, then you assign it. If you wish to use that particular keystroke in a Parallels window, then you unassign it in the host OS and it will pass thru. This is how Linux works and I'm sure that Mac does too.
For example: Some Linuxs' use ctrl-alt-delete to initiate a shutdown. I use a lot of windoze VMs and would rather use those keys to bring up the Task Manager to kill a frozen app in windoze. So I unassign those keys in Linux, and they are passed to the windoze VM, but only if the VM has the focus. Otherwise it is ignored by Linux since it is disabled. I'm almost certain that some sort of host OS windowing system interaction would be needed to do dynamic switching based on which particular window had the focus to change the effect of a key stroke action. You're right that there is no possibility for a (proprietary) guest to pass back a key stroke to the host.
Last edited: Dec 12, 2006