$.fn.disable = function() {
return this.each(function() {
if (typeof this.disabled != "undefined") this.disabled = true;
});
}

$.fn.enable = function() {
return this.each(function() {
if (typeof this.disabled != "disabled") this.disabled = false;
});
}

$(function() {
	//Disable submit button:
	$("#dc-submit-button").disable();
	//Add click function to each checkbox:
	$("INPUT[type='checkbox']").click(function() { 
	//If a checkbox is checked show submit button
	if($("INPUT[type='checkbox']:checked").val()) {
	 $("#dc-submit-button").enable();
	 } else {
	 $("#dc-submit-button").disable();	
	 }
	});
});