percent = 0;
timer = 50;
oldseq = 1;
oldtab = "nav1";

function execFade(newseq){
    newid = "original" + newseq;
    oldid = "original" + oldseq;
    document.getElementById(oldid).style.display = "none";
    document.getElementById(newid).style.display = "block";
    percent = 0;
    oldseq = newseq;
    Fade(newid);
}

function Fade(newid){
    if (percent <= 100){
	document.getElementById(newid).style.filter = "alpha(opacity:" + percent + ")";
	document.getElementById(newid).style.opacity = percent / 100;
	percent += 5;
	setTimeout("Fade('" + newid + "')", timer);
    }
}

function swapTab(newtab, startseq){
    document.getElementById(oldtab).style.display = "none";
    document.getElementById(newtab).style.display = "block";
    oldtab = newtab;
    execFade(startseq);
}

window.onload = function(){
    swapTab("nav1", 1);
};