Done button for multi-selection

[hongpower]

Hello.
I know multi-selection can be handled by multiSelectionAction handler.
I want to add a "done" button so that the user can hide the dropDown after finishing selecting cells.

The only way i found so far is by using dataSource. By adding extra "done" string in datasources and when the "done" cell index is selected, call dropDown.hide()
But I am pretty sure there can be a better way for this.

Thank you.