How to make Expo list windows from all workspaces?
This is not a bug, but a configuration issue. You need to install Compizconfig-settings-manager from the Software Center, and then, when you run it, go to the scale plugin.
From here, you have to set the option "Initiate Window Picker For All Windows" to use Super+w. This will complain of a conflict, but all you have to do is disable "Initiate Window Picker".
You can begin using it immediately.
As of 14.04, you could expo windows from all workspaces using
Shift+Win+W