function makeThrobber (imgPath) 
{
	var throbElem = document.createElement('img');
	throbElem.setAttribute('id', 'throbber');
	throbElem.setAttribute('src', imgPath);
	throbElem.style.visibility = 'hidden';
	return throbElem;
}

function swapThrobber (encElemId, swapElemId, throbElemId)
{
	var encElem   = document.getElementById(encElemId);
	var swapElem  = document.getElementById(swapElemId);
	var throbElem = document.getElementById(throbElemId);
	encElem.removeChild(swapElem);
	document.getElementById(throbElemId).style.visibility = 'visible';
}