This example shows how to select multiple options.
In addition, the allowDeselection property is set to true to allow the user to deselect an option and the closeOnSelect property is set to false to keep the popover open after selecting an option.
If you tap outside the popover, it will close.
The allowDeselection property is present only in the ShadSelect.multiple constructor, to use it in a normal select use onChangedNullable instead of onChanged.