function $(s) { return document.getElementById( s ); }

function attachEventToElement ( element, eventName, handler, settingCapture )
{
    if ( settingCapture != true ) settingCapture = false;  // cast to Boolean
    
    switch ( eventName ) 
    {
    case "load":
        if ( element.addEventListener ) { element.addEventListener( "load", handler, settingCapture ); }
        else if ( element.attachEvent ) { element.attachEvent( "onload", handler ); } 
        else { element.onload = handler; }
        break;

    case "mouseover":
        if ( element.addEventListener ) { element.addEventListener( "mouseover", handler, settingCapture ); }
        else if ( element.attachEvent ) { element.attachEvent( "onmouseover", handler ); } 
        else { element.onmouseover = handler; }
        break;

    case "mouseout":
        if ( element.addEventListener ) { element.addEventListener( "mouseout", handler, settingCapture ); }
        else if ( element.attachEvent ) { element.attachEvent( "onmouseout", handler ); } 
        else { element.onmouseout = handler; }
        break;
    }
}

function detachEventFromElement ( element, eventName, handler, capture )
{
    if ( capture != true ) capture = false;  // cast to Boolean
    
    switch ( eventName ) 
    {
    case "load":
        if ( document.removeEventListener ) { document.removeEventListener( "load", handler, capture ); }
        else if ( element.detachEvent ) { element.detachEvent( "onload", handler ); }
        else { element.onload = null; }
        break;
    }
}

function displayRow (layerName) {
	document.getElementById(layerName).style.display='block';
}

function displayNone (layerName) {
	document.getElementById(layerName).style.display='none';
}
	
function closeAll() { 
	displayNone('layer1'); 
	displayNone('layer2');
	displayNone('layer3');
	displayNone('layer4');
	displayNone('layer5');
	displayNone('layer6');
	displayNone('layer7');
	displayNone('layer8');
}	

var pos = 1;
function move_layer(direction, pos_num, last_num) { 
	document.getElementById('layer'+pos).style.display='none';
	if (direction == 0) {
		pos = pos_num;
	} else {
		document.getElementById('layer'+pos).style.display='none';
		if ((pos < last_num) && (direction == 1))
			pos += direction;
		if ((pos > 1) && (direction == -1))
			pos += direction;
	}
	document.getElementById('layer'+pos).style.display='block';
}