//global variables that can be used by ALL the function son this page.
var inputs;
var imgFalse = 'images/oncheck.gif';
var imgTrue = 'images/onchecked.png';

//this function runs when the page is loaded, put all your other onload stuff in here too.
function start() {
	replaceChecks();
}

function replaceChecks() {
	
	//get all the input fields on the page
	inputs = document.getElementsByTagName('input');

	//cycle trough the input fields
	for(var i=0; i < inputs.length; i++) {

		//check if the input is a checkbox
		if(inputs[i].getAttribute('type') == 'checkbox') {
			
			//create a new image
			var img = document.createElement('images');
			
			//check if the checkbox is checked
			if(inputs[i].checked) {
				img.src = imgTrue;
			} else {
				img.src = imgFalse;
			}

			//set image ID and onclick action
			img.id = 'checkImage'+i;
			//set image 
			img.onclick = new Function('checkChange('+i+')');
			//place image in front of the checkbox
			inputs[i].parentNode.insertBefore(img, inputs[i]);
			
			//alterar o link para permitir marcar e desmarcar
			inputs[i].nextSibling.href = 'javascript:checkChange('+i+');';
																
			//hide the checkbox
			inputs[i].style.display='none';
		}
	}
}

//change the checkbox status and the replacement image
function checkChange(i) {

	if(inputs[i].checked) {
		inputs[i].checked = '';
		document.getElementById('checkImage'+i).src=imgFalse;
	} else {
		inputs[i].checked = 'checked';
		document.getElementById('checkImage'+i).src=imgTrue;
	}
}

// para fazer o supersleight e esse script funcionarem ao mesmo tempo
var oldonload=window.onload;
if(typeof window.onload!='function') {
	window.onload=start;
} else {
	window.onload=function(){
		if(oldonload){
			oldonload();
		}
		start();
	}
}