function changecolor(layer_name)
{
var layer = document.getElementById(layer_name);
layer.style.background = "#ffffff";
//layer.style.background = (layer.style.background == "#000000" ? "#ffffff" : "#000000" );
}

function changecolor(layer_name)
{
var layer = document.getElementById(layer_name);
layer.style.background = "#ffffff";
//layer.style.background = (layer.style.background == "#000000" ? "#ffffff" : "#000000" );
}