// Toggle Layer style for left property
function togLyr (el, status) { 
    var wdd = (status == 1) ? "0" : "-999em";
    document.getElementById(el).style.left = wdd;
}

// Clear all left properties
function clrLyr() {
	togLyr('f1','0');
	togLyr('f2','0');
	togLyr('f3','0');
	togLyr('f4','0');
}