function preloadImages(){
    left_nav_1 = new Image();
    left_nav_1.src = "intro/gfx/icon-box-15_on.gif";
    left_nav_2 = new Image();
    left_nav_2.src = "intro/gfx/icon-box-16_on.gif";
    left_nav_3 = new Image();
    left_nav_3.src = "intro/gfx/icon-box-17_on.gif";
    left_nav_4 = new Image();
    left_nav_4.src = "intro/gfx/icon-box-18_on.gif";
    left_nav_5 = new Image();
    left_nav_5.src = "intro/gfx/icon-box-19_on.gif";
    left_nav_6 = new Image();
    left_nav_6.src = "intro/gfx/icon-box-20_on.gif";
    left_nav_7 = new Image();
    left_nav_7.src = "intro/gfx/icon-box-21_on.gif";
    left_nav_8 = new Image();
    left_nav_8.src = "intro/gfx/icon-box-22_on.gif";
    left_nav_9 = new Image();
    left_nav_9.src = "intro/gfx/icon-box-23_on.gif";
    teaser_link = new Image();
    teaser_link.src = "intro/gfx/teaser_link.gif";
    teaser_link_hover = new Image();
    teaser_link_hover.src = "intro/gfx/teaser_link_hover.gif";
}

function switchClass(id){

    if(document.getElementById(id).className == 'left_text_hidden'){

        document.getElementById(id).className = 'left_text_visible';

    }
    else{
        document.getElementById(id).className = 'left_text_hidden';
    }

}
// Funktion zur Referenzierung von Div-Layern mit Zugriff auf CSS-Eigenschaften
function div_ref_style (id) {
    if      (document.layers)         return document.layers[id];
    else if (document.all)            return document.all[id].style;
    else if (document.getElementById) return document.getElementById(id).style;
    else                              return null;
}

// Funktion zum Zeigen und Verstecken von Div-Layern
function handle_layer (id,stat) {

    try
    {
        div_ref_style(id).visibility =  stat ? "visible" : "hidden";
    } catch (ex)
{
    }
}