So it looks like with the MultiSelectDropDowns if I move the Validator.required()
method to the form_show
event, it works as expected - even in an alert.
It turns out that this not related to the form_show
event but rather something to do with setting the items of the MultiSelectDropDowns after the Validator.required()
method.
Setting the items first and the the validator
fixes this issue. Thanks very much for your help.