Choosing which commons a bar uses

Commons are opt-in per bar - a new bar uses none until you add them - and the selection is ordered, so you control which shared sets each context shows and in what sequence. You set this on each non-common bar's card in Settings.

• Commons - the list of common bars this bar currently pulls in, in prepend order.
• Add a common bar… - pick a common bar from the dropdown and confirm to add it to this bar's list.
• Remove from this bar - drop a common from this bar's list (it stays a common bar; this bar just stops using it).