Keyboard shortcuts that use windows key do not work

[Hubert depesz Lubaczewski]

I installed KUbuntu 15.04 on fresh system, and noticed that when I make a session, and assign keyboard shortcut to run this session (like ctrl-shift-t runs new "Shell') - it works, as long as the shortcut doesn't use windows key.

I can enter such shortcut, and it's displayed correctly as "Meta+M" (for example), but upon pressing windows-m, I'm getting some control characters sent to terminal, and not new tab opened with defined session.

It looks, that (at least for meta-m) the generated sequence is: "ctrl-x", "@", "s", "m".