Save date property from multifield in dialog

[alistairp781078]

I'm currently developing a multifield field in a dialog and am wondering how to change the property type for the values saved back to the repo.

In the JS code that's used to save the values from the dialog, there's this:

        $('<input />').attr('type', 'hidden')

            .attr('name', fieldSetName + "/par" + counter + "/" + name)

            .attr('value', value)

            .appendTo($form);

As far as I know, this is ultimately adding the value for a field from the multifield to a relative path in the repo. It always saves the value as a string:

Is it possible to change the property type from string to something else? For instance, in the example screenshot above, I would like to save that value with a date type.