function openPopup(pUrl, pWidth, pHeight){
	var _width = 0; var centered_width = 0; _width = screen.availWidth;
	var _height = 0; var centered_height = 0; _height = screen.availHeight;
	if (_width>pWidth) centered_width = (_width-pWidth)/2;
	if (_height>pHeight) centered_height = (_height-pHeight)/2;
	viewer = window.open(pUrl,"viewer","top="+centered_height+",left="+centered_width+",status=yes,scrollbars=yes,menubar=no,resizable=yes,width="+pWidth+",height="+pHeight);
	viewer.focus();
}