When I use a keyboard layout with keys that are not from basic latin, and I press a non-basic-latin letter in conjunction with Ctrl the following happens:

• The VirtualKeyCode seems to be the character at the same location from the US layout.
• The ReceivedCharacter is sometimes identical to the VirtualKeyCode but it's sometimes an ASCII control character.

This happens on both Linux with X11 and on Windows. Actually, on Windows the ReceivedCharacter isn't even sent for some combinations.

The issue is that it seems the application has no way of telling what was the original key pressed. So for example if I'm using a Hungarian layout and I press Ctrl+ű I get a '\u{1c}' in ReceivedCharacter and my applications has no idea that ű was ever pressed. This may not be relevant for text input but it's relevant for shortcuts.