Pre-submit modal popup and then submit

I have a quick contact form on a site. Before the user submits the form, I want to show a modal popup saying "Are you sure you're not looking for XXX" if not "Submit the parent form.

I've added the following js to my form (form displayed as a module) and changed the form tag attachment to onsubmit="showModal();return false;"

How can I submit the parent form from the modal?

function showModal() {

	$conv_ = jQuery;
	var options = {size: {x: 300, y: 150}};
	SqueezeBox.initialize(options);
	SqueezeBox.setContent('string',jQuery("#presubmitmessage").html());
}

function submitquick() {
parent.form.submit();
}