function listboxcheck(){

		if(document.forms['frmSearch'].elements['landkreis'].length == 1){
			listboxklick();
		}
	
	}
	
	function listboxklick(){
	
		var bMozilla = (document.getElementById)? 1:0;
		for(i=0;i<=document.forms['frmSearch'].elements['landkreis'].length-1;i++){
			if(document.forms['frmSearch'].elements['landkreis'][i].selected == true){
				togglelayervisibility('kreis'+document.forms['frmSearch'].elements['landkreis'][i].value);
				
				if (bMozilla) {
					document.forms[0].elements['landkreis'].options[i]=null;
				} else {
					document.forms[0].elements['landkreis'].options.remove(i);
				}
				
			}
		}

		for(i=0;i<=document.forms['frmSearch'].elements['landkreis'].length-1;i++){
			document.forms['frmSearch'].elements['landkreis'][i].selected = true;
		}
		
		if(document.forms['frmSearch'].elements['landkreis'].length == 1){
			document.forms['frmSearch'].elements['flaeche_von'].focus();
		}
	}
		
	function togglelandkreis(Kennzahl,Name){

		var i;
		var bFlag = false;
		var iIndex = 0;

		bFlag = false;
		for(i=0;i<=document.forms['frmSearch'].elements['landkreis'].length-1;i++){
			if(document.forms['frmSearch'].elements['landkreis'][i].value == Kennzahl){
				bFlag = true;
				iIndex = i;
			}
		}
		
		if(bFlag){
			//löschen
			//document.forms[0].elements['landkreis'].options.remove(iIndex);
			document.forms[0].elements['landkreis'].options[iIndex]=null;
		}else{
			//hinzufügen und markieren
			var option = new Option(Name, Kennzahl);
			var select = document.forms['frmSearch'].elements['landkreis'];
			var NumObjects = document.forms['frmSearch'].elements['landkreis'].length;

			select.options[select.options.length] = option;
			document.forms['frmSearch'].elements['landkreis'][NumObjects].selected = true;
		}
	}

	function togglelandkreisWiFoe(Kennzahl,Name){

		var i;
		var bFlag = false;
		var iIndex = 0;
				
		bFlag = false;
		for(i=0;i<=document.forms['frmSearch'].elements['landkreis'].length-1;i++){
			if(document.forms['frmSearch'].elements['landkreis'][i].value == Kennzahl){
				bFlag = true;
				iIndex = i;
			}
		}
		
		if(bFlag){
			document.forms[0].elements['landkreis'].options[iIndex]=null;
		}else{
			var option = new Option(Name, Kennzahl);
			var select = document.forms['frmSearch'].elements['landkreis'];
			var NumObjects = document.forms['frmSearch'].elements['landkreis'].length;

			select.options[select.options.length] = option;
			//document.forms['frmSearch'].elements['landkreis'][NumObjects].selected = true;
		}

		for(i=0;i<=document.forms['frmSearch'].elements['landkreis'].length-1;i++){
			document.forms['frmSearch'].elements['landkreis'][i].selected = true;
		}
	}

	function togglelayervisibility(id_layer){
		
		var bMozilla = (document.getElementById)? 1:0;
		if(bMozilla){
			//Mozilla
			if(document.getElementById(id_layer).style.visibility == 'hidden'){
				document.getElementById(id_layer).style.visibility = 'visible';
			}else{
				document.getElementById(id_layer).style.visibility = 'hidden';
			}
		}else{
			//Sonstige
			if(document.all[id_layer].style.visibility == 'hidden'){
				document.all[id_layer].style.visibility = 'visible';
			}else{
				document.all[id_layer].style.visibility = 'hidden';
			}
		}
	}