function getLayer(name)
{
	return document.getElementById(name);
}


function hideLayer(layer)
{
	layer.style.visibility = "hidden";
}

function showLayer(layer)
{
	layer.style.visibility = "visible";
}

function reverseVisibility(layer)
{
    if (getVisibility(layer) == "visible")
        hideLayer(layer);
    else
        showLayer(layer);
}


function getVisibility(layer)
{
	return layer.style.visibility;
}

function hideAll()
{
  hideLayer(getLayer('galitem01'));
  hideLayer(getLayer('galitem02'));
  hideLayer(getLayer('galitem03'));
  hideLayer(getLayer('galitem04')); 
}