function mopen(id, back)
{	
	// is the current id the same as the last tab?
	if(last_tab != id){
		// no, so revert the last tab to it's idle state.
		revert_tab_image(last_tab);
	}
	// set last tab to current tab to save its state
	last_tab = id;
	// note that we're over the menu
	over_menu = true;
	// cancel close timer
	mcancelclosetime();

	// close old layer
	if(ddmenuitem) hideNavElement(ddmenuitem);
    // get new layer and show it
    ddmenuitem = document.getElementById(id);
    pos = ddmenuitem.parentNode.style.left;
    ddmenuitem.style.left = pos;


}
function hideNavElement(el) {
	el.style.position = 'absolute';
	el.style.left = '-999px';
}

// close showed layer
function mclose()
{
	try{
	//only close if we're not over the menu
	if(!over_menu){
		if(ddmenuitem) hideNavElement(ddmenuitem);
		// revert last tab to idle state
		revert_tab_image(last_tab);		
	}
	} catch(e){}
}

// go close timer
function mclosetime()
{
	//not over menu, note it
	over_menu = false;
	closetimer = window.setTimeout("mclose()", timeout);
}

// cancel close timer
function mcancelclosetime()
{
	//we're over menu, so note it
	over_menu = true;
	if(closetimer)
	{
		window.clearTimeout(closetimer);
		closetimer = null;
	}
}
// reverts tab to idle state
function revert_tab_image(id){

}