Why does X11 generate an extra SHIFT when I press Shift+KP_1 ?

[wettstae at gmail.com]

> So the question is that is there any way VirtualBox can be causing this, I
> don't think it is interfering but you be the judge of that.

I suspect that this is the root of the weird behaviour.

One can think of various way of mapping key events from host to guest.
The one extreme is to do the mapping based on physical keys.  The other
extreme is that given the "keysym" entered at the host, one looks up the
same keysym in the guest layout, and then sends the guest the key
press/release events to get that keysym with that layout.  For example,
VNC uses approach similar to the latter, and maybe VirtualBox does, too.

For testing this hypothesis, you could switch the guest to a different
layout, for example, de, which among others swaps y and z.  You keep the
host at US layout.  If the guest still behaves as if it would use a US
layout (and, in particular, you can enter y and z using their US
positions), it is clear proof that VirtualBox uses some sort of "keysym"
based mapping strategy.

Andreas