need way to close field selection list once opened

in the search bar, there's the 'Choose fields...' link that drops open a large list of fields for selection. Can we add a way to close this list? Then when the list ifs closed instead of 'Choose fields...', show the selected fields with a clear button, like 'Title, Subject [X]'. Clicking on 'Title, Subject' would open the list again, clicking of the X would unselect all field selections and revert the link back to 'Choose fields...'