function modal(a) {
  var modal = new Control.Modal(a, {
    opacity: 0.8,
    fade: true,
    afterOpen: function() {
		  var height = $('container').getHeight()+$('footer').getHeight();
		  
		  if (document.viewport.getHeight() > height) {
		    height = document.viewport.getHeight();
		  }
		  
		  $('modal_overlay').setStyle({height: height+'px'});
		}
  });
  
  modal.open();
  
  return false;
}