function setCenterImage( pImageElement )
{
	var zSmallImgTitle = pImageElement.title;
	var zImgText = pImageElement.alt;
	
	var zSmallImgSrc = pImageElement.src;
	var zDotIndex = zSmallImgSrc.lastIndexOf(".");
	
	var zCenterImageElement = document.getElementById("center_image");
	
	if( zCenterImageElement )
	{
		//var imgName = zSmallImgSrc.substring(0, zDotIndex);
		//var appendix = "_large";
		//var imgExtension = zSmallImgSrc.substring(zDotIndex);
		
		//zCenterImageElement.src = imgName + appendix +  imgExtension;
		
		zCenterImageElement.src = zSmallImgSrc.substring(0, zDotIndex) + "_large" +  zSmallImgSrc.substring(zDotIndex);
		
	}
	
	var zCenterImageText = document.getElementById("img_text");
	if( zImgText != "" && zCenterImageText )
	{
		zCenterImageText.innerHTML = zImgText;
	}
    
	var zCenterImageTitle = document.getElementById("img_title");
	if( zSmallImgTitle != "" && zCenterImageTitle )
	{
		zCenterImageTitle.innerHTML = zSmallImgTitle;
	}	
}

/** This is high-level function; REPLACE IT WITH YOUR CODE.
 * It must react to delta being more/less than zero.
 */
function handle(delta) 
{
	var zThumbsPanel = document.getElementById("thumbs_panel");
	var zTop = parseInt(zThumbsPanel.style.top);
	var zMultiplier = 30;
	
	if (delta < 0)
	{
		//window.status = "down: "+ delta + " Top:" + zTop + " absTop:" + Math.abs(zTop) + " panelHeight:" + zThumbsPanel.offsetHeight;
		
		if ( Math.abs(zTop) < (zThumbsPanel.offsetHeight - 580) )
		{
			zThumbsPanel.style.top = zTop + (delta * zMultiplier) + "px";
		}
	}
	else
	{	
		//window.status = "up: "+ delta + " Top:" + zTop + " absTop:" + Math.abs(zTop) + " panelHeight:" + zThumbsPanel.offsetHeight;
		if (zTop < 0)
		{
		
			zThumbsPanel.style.top = zTop + (delta * zMultiplier) + "px";
		}
	}
}

function wheel(event){
	var delta = 0;
	if (!event) event = window.event;
	if (event.wheelDelta) 
	{
		delta = event.wheelDelta/120; 
		if (window.opera) delta = -delta;
	} else if (event.detail) 
	{
		delta = -event.detail/3;
	}
	if (delta)
		handle(delta);
        if (event.preventDefault)
                event.preventDefault();
        event.returnValue = false;
}