function fundoInput(obj,img)
{
	obj.onblur = obj.onfocus;
	obj.onkeyup = obj.onfocus;
	obj.onkeypress = obj.onfocus;
	obj.onkeydown = obj.onfocus;
	if(obj.value.length)
		obj.style.backgroundImage = 'url()';
	else
		obj.style.backgroundImage = 'url('+img+')';
}