doesn't map to anything via AltGr. This is an improvement over
the previous code which would simply discard the key but it
still behaves slightly differently than pressing ctrl+alt+<key>
on the server: if that combination is a hotkey on the server
then the hotkey is performed, even if the combination is also
a valid AltGr combination; on the client, we'll get the AltGr
combination in preference to the hotkey.
using low-level keyboard hooks, fixed handling of the global
keyboard layout dead key buffer, fixed identification of dead
keys, fixed synthesis of AltGr (now using right-alt instead
of left-alt), now using VK_DECIMAL for Separator key, fixed
bug where an unmappable key was treated as virtual key 0xff,
and added support for shift-space (shift was being discarded).
Also fixed failure to hide cursor when leaving primary screen
and added support for handling PrintScreen key.
crs