Plone - How can I get the Reccurence widget to appear at the top of a form opened opened as an overlay?

Question

I have a dexterity content type that includes the IEventBasic and IEventRecurrence behaviors (as defined in the type's xml file). Using jQuery, my object type's form is opened in an overlay through 'prepOverlay'. When I try to add a Recurrence rule through the Recurrence field though, the recurrence field's own overlay form ends up appearing below the overlay.

One thing I did try was using css to change the z-index of the recurrence overlay so that it would appears in front. However, there is an issue with the "dimmer" div. It seems that the recurrence overlay is trying to use the same dimmer as the main overlay.

.riform { 
    z-index:11000;   
}

.calroot{
    z-index:11010;
}

Two things happen:

-When I first open the form and click on recurrence, the dimmer appears behind the main overlay, so I can still edit the widgets in the main overlay despite the popup overlay being present.

-Then when I open the form every other time, the overlay appears in front of the (which technically it should be doing this), but when I click on the dimmer, it closes the main overlay on top of the recurrence's overlay.

I also needed to change the z-index of the calendar widget because it was appearing below everything as well.

Is there a way to work around this? Or is this problem related to another problem?

I assign prepoverlay in a javascript file like:

jQuery(function($){
    $("a#my-event-type").prepOverlay(
        {
            subtype: 'ajax',
            filter: '#content>*',
            formselector: '#content-core > form',
            noform: function(el){
                return 'reload';
            },
        }
    );
});

I am using Plone 4.3 and the version of plone.app.event (where the behaviors are) is 1.1.6.