I can confirm that I can set this option in Tweak Tool. In Typing, I set Key(s) to Change Layout to Alt+Shift.
GNOME Shell recognized the new option (Super+Space still worked too) but Unity did not recognize it.
This is what Tweak Tool set:
$ gsettings get org.gnome.desktop.input-sources xkb-options ['compose:ralt', 'grp:alt_shift_toggle']
I can confirm that I can set this option in Tweak Tool. In Typing, I set Key(s) to Change Layout to Alt+Shift.
GNOME Shell recognized the new option (Super+Space still worked too) but Unity did not recognize it.
This is what Tweak Tool set:
$ gsettings get org.gnome. desktop. input-sources xkb-options shift_toggle' ]
['compose:ralt', 'grp:alt_