Comment 49 for bug 1313446

As this bug most likely won't ever get fixed (since Unity7 development was scrapped), it might be useful to document the known workarounds here, starting with:

1: Start any window manager with working shade support, for example as follows:
$ nohup openbox --replace >/dev/null &
# Warning: If you are not familiar with openbox and alike, their default settings are rather minimalistic; no taskbars or app menus included after the replace above (see https://help.ubuntu.com/community/Openbox for more details).

2: Disable any references to shading if you want/need to use Unity
$ gsettings list-recursively org.gnome.desktop.wm.keybindings | grep -i shade
$ gsettings list-recursively org.gnome.desktop.wm.preferences | grep -i shade
$ # ... followed by some form of gsettings set or reset to the ones listed (not tested)