function hideLayer(layerName)
{
	var style = document.getElementById(layerName).style;
	style.display = "none";
}

function showLayer(layerName)
{
	var style = document.getElementById(layerName).style;
	style.display = "block";
}

function hideAll()
{
    hideLayer('horten');
    hideLayer('namsos');
    hideLayer('oslo');
    hideLayer('stjordal');
    hideLayer('trondheim');
    hideLayer('verdal');
    hideLayer('alesund');
    hideLayer('engros');
}