var default_logo_src = null;

function change_logo_to (new_src)
{
	if (default_logo_src == null)
		default_logo_src = document.getElementById("top_left_logo").pngSrc;
	if (default_logo_src == null)
		default_logo_src = document.getElementById("top_left_logo").src;
	document.getElementById("top_left_logo").src = new_src;
}

function revert_logo ()
{
	if (default_logo_src != null)
		document.getElementById("top_left_logo").src = default_logo_src;
}