function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      if (oldonload) {
        oldonload();
      }
      func();
    }
  }
}

function addEvent( obj, type, fn ) {
  if(obj){
    if ( obj.attachEvent ) {
          obj['e'+type+fn] = fn;
          obj[type+fn] = function(){obj['e'+type+fn]( window.event );}
          obj.attachEvent( 'on'+type, fn );
      } else {
          obj.addEventListener( type, fn, false );
      }
  }
}

function newImage(arg) {
  if (document.images) {
    rslt = new Image();
    rslt.src = arg;
    return rslt;
  }
}

function changeImages() {
  if (document.images && (preloadFlag == true)) {
    for (var i=0; i<changeImages.arguments.length; i+=2) {
      document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
    }
  }
}

var preloadFlag = false;
function preloadImages() {
  if (document.images) {
    nav1_over = newImage("../images/nav/nav1-over.gif");
    nav1_down = newImage("../images/nav/nav1-down.gif");
    nav2_over = newImage("../images/nav/nav2-over.gif");
    nav2_down = newImage("../images/nav/nav2-down.gif");
    nav3_over = newImage("../images/nav/nav3-over.gif");
    nav3_down = newImage("../images/nav/nav3-down.gif");
    nav4_over = newImage("../images/nav/nav4-over.gif");
    nav4_down = newImage("../images/nav/nav4-down.gif");
    preloadFlag = true;
  }
}

function addHandlers() {
  var W3CDOM = (document.createElement && document.getElementsByTagName);
  if (!W3CDOM) {
        return;
    }
    addEvent(document.getElementById('nav1'), 'mouseover', function(){changeImages('nav1', '../images/nav/nav1-over.gif'); return true;});
    addEvent(document.getElementById('nav1'), 'mouseout', function(){changeImages('nav1', '../images/nav/nav1.gif'); return true;});
    addEvent(document.getElementById('nav1'), 'mousedown', function(){changeImages('nav1', '../images/nav/nav1-down.gif'); return true;});
    addEvent(document.getElementById('nav1'), 'mouseup', function(){changeImages('nav1', '../images/nav/nav1-over.gif'); return true;});

    addEvent(document.getElementById('nav2'), 'mouseover', function(){changeImages('nav2', '../images/nav/nav2-over.gif'); return true;});
    addEvent(document.getElementById('nav2'), 'mouseout', function(){changeImages('nav2', '../images/nav/nav2.gif'); return true;});
    addEvent(document.getElementById('nav2'), 'mousedown', function(){changeImages('nav2', '../images/nav/nav2-down.gif'); return true;});
    addEvent(document.getElementById('nav2'), 'mouseup', function(){changeImages('nav2', '../images/nav/nav2-over.gif'); return true;});

    addEvent(document.getElementById('nav3'), 'mouseover', function(){changeImages('nav3', '../images/nav/nav3-over.gif'); return true;});
    addEvent(document.getElementById('nav3'), 'mouseout', function(){changeImages('nav3', '../images/nav/nav3.gif'); return true;});
    addEvent(document.getElementById('nav3'), 'mousedown', function(){changeImages('nav3', '../images/nav/nav3-down.gif'); return true;});
    addEvent(document.getElementById('nav3'), 'mouseup', function(){changeImages('nav3', '../images/nav/nav3-over.gif'); return true;});

    addEvent(document.getElementById('nav4'), 'mouseover', function(){changeImages('nav4', '../images/nav/nav4-over.gif'); return true;});
    addEvent(document.getElementById('nav4'), 'mouseout', function(){changeImages('nav4', '../images/nav/nav4.gif'); return true;});
    addEvent(document.getElementById('nav4'), 'mousedown', function(){changeImages('nav4', '../images/nav/nav4-down.gif'); return true;});
    addEvent(document.getElementById('nav4'), 'mouseup', function(){changeImages('nav4', '../images/nav/nav4-over.gif'); return true;});

    addEvent(document.getElementById('nav5'), 'mouseover', function(){changeImages('nav5', '../images/nav/nav5-over.gif'); return true;});
    addEvent(document.getElementById('nav5'), 'mouseout', function(){changeImages('nav5', '../images/nav/nav5.gif'); return true;});
    addEvent(document.getElementById('nav5'), 'mousedown', function(){changeImages('nav5', '../images/nav/nav5-down.gif'); return true;});
    addEvent(document.getElementById('nav5'), 'mouseup', function(){changeImages('nav5', '../images/nav/nav5-over.gif'); return true;});

    addEvent(document.getElementById('nav6'), 'mouseover', function(){changeImages('nav6', '../images/nav/nav6-over.gif'); return true;});
    addEvent(document.getElementById('nav6'), 'mouseout', function(){changeImages('nav6', '../images/nav/nav6.gif'); return true;});
    addEvent(document.getElementById('nav6'), 'mousedown', function(){changeImages('nav6', '../images/nav/nav6-down.gif'); return true;});
    addEvent(document.getElementById('nav6'), 'mouseup', function(){changeImages('nav6', '../images/nav/nav6-over.gif'); return true;});

    addEvent(document.getElementById('nav7'), 'mouseover', function(){changeImages('nav7', '../images/nav/nav7-over.gif'); return true;});
    addEvent(document.getElementById('nav7'), 'mouseout', function(){changeImages('nav7', '../images/nav/nav7.gif'); return true;});
    addEvent(document.getElementById('nav7'), 'mousedown', function(){changeImages('nav7', '../images/nav/nav7-down.gif'); return true;});
    addEvent(document.getElementById('nav7'), 'mouseup', function(){changeImages('nav7', '../images/nav/nav7-over.gif'); return true;});

    addEvent(document.getElementById('nav8'), 'mouseover', function(){changeImages('nav8', '../images/nav/nav8-over.gif'); return true;});
    addEvent(document.getElementById('nav8'), 'mouseout', function(){changeImages('nav8', '../images/nav/nav8.gif'); return true;});
    addEvent(document.getElementById('nav8'), 'mousedown', function(){changeImages('nav8', '../images/nav/nav8-down.gif'); return true;});
    addEvent(document.getElementById('nav8'), 'mouseup', function(){changeImages('nav8', '../images/nav/nav8-over.gif'); return true;});

}

function isLowRes() {
  //returns true if in a low-resolution environment (width <= 800 pixels)
  if (self.screen)
    return (screen.width <= 800);
  else
    return false;
}

function changeStylesLoRes() {
    if (isLowRes()) {
        if (document.getElementById) {
       alert('schermresolutie = ' + screen.width);
            var nodeObj = document.getElementById('wrapper');
       nodeObj.style.width = '780px';

            nodeObj = document.getElementById('header');
            nodeObj.style.marginLeft = '0px';
            nodeObj.style.marginRight = '0px';

            nodeObj = document.getElementById('content');
            nodeObj.style.marginLeft = '0px';
            nodeObj.style.marginRight = '0px';

            nodeObj = document.getElementById('footer');
            nodeObj.style.width = '780px';
            nodeObj.style.background = 'url(../images/widgets/footer-small.jpg) no-repeat';
        }
    }
}

function hoverNcdoTab() {
	var tab = document.getElementById('ncdoLabels');
	if (tab.style.backgroundColor == "#5D106E" || tab.style.backgroundColor == "#5d106e" || tab.style.backgroundColor == "rgb(93, 16, 110)") {
		tab.style.backgroundColor = "#C4C4C4";
	} else {
		tab.style.backgroundColor = "#5D106E";
	}
}
addLoadEvent(preloadImages)
addLoadEvent(addHandlers)
addLoadEvent(sifrSwitch)
addLoadEvent(changeStylesLoRes)