IBus binds Super+space to switch the input method engines by default.
When users press Super+space, the space char is output and Super+space+space can switch engines in Cinnamon desktop. This does not happen in other desktops.

To reproduce:
1. Log into Cinnamon desktop.
2. Run ibus-daemon if it does not.
% ibus-daemon --xim &
3. Run ibus-setup and open "Input Method" tab and add more than two IMEs.
4. Press Super+space

And then Super+space does not switch IMEs.

Expected result:
Cinnamon binds "Super" key only but not "Super+space".
Super+space can switch IMEs.

Workaround:
Run cinnamon-settings and select "Applet" -> "Menu" and click "Settings" button.
Change the short cut "Super_L" in "Keyboard shortcut to open and close menu" to "<Super>Up".