//globale variable om in bij te houden of er op een link <a>-tag is geklikt.
 //Indien true, dan niet van stijl wisselen.
 var cancelStyleChange = false;
 document.onmousedown = handleMouseClick;
 
 //bepaalt het bron element waarop geklikt is (IE & FF compatible)
 function handleMouseClick(e) {
    var targ;
    if (!e) var e = window.event;
    if (e.target) targ = e.target;
    else if (e.srcElement) targ = e.srcElement;
    if (targ.nodeType == 3) // defeat Safari bug
        targ = targ.parentNode;
        
     cancelStyleChange = (targ.tagName == 'A'); 
		            
  }
 
 
 function onMouseOverEff(pvItem, pvStandard, pvStandardOver, pvActive, pvActiveOver)
    {
        var lvCurrent;
        lvCurrent = pvItem.className;
        
        switch(lvCurrent)
        {
        case pvStandard:
          pvItem.className = pvStandardOver;
          break;
        case pvActive:
          pvItem.className = pvActiveOver;
          break;
        }   
    }

    function onMouseOutEff(pvItem, pvStandard, pvStandardOver, pvActive, pvActiveOver)
    {
        var lvCurrent;
        lvCurrent = pvItem.className;
        
        switch(lvCurrent)
        {
        case pvStandardOver:
          pvItem.className = pvStandard;
          break;
        case pvActiveOver:
          pvItem.className = pvActive;
          break;
        }       
    }

    function onMouseClickEff(pvItem, pvStandard, pvStandardOver, pvActive, pvActiveOver)
    {
        //cancelStyleChange is true als er op een link (A-tag) is geklikt.
        if (cancelStyleChange) return false;
         
        var lvCurrent;
        lvCurrent = pvItem.className;
        
        switch(lvCurrent)
        {
        case pvStandard:
          pvItem.className = pvActive;
          break;
        case pvStandardOver:
          pvItem.className = pvActiveOver;
          break;
        case pvActive:
          pvItem.className = pvStandard;
          break;
        case pvActiveOver:
          pvItem.className = pvStandardOver;
          break;
        }
    }