var popUpWin=0;
			function popUpWindow(URLStr, left, top, width, height){
				if(popUpWin){
					if(!popUpWin.closed) popUpWin.close();
				}
				popUpWin = open(URLStr, 'popUpWin', 'toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbar=no,resizable=no,copyhistory=yes,width='+width+',height='+height+',left='+left+', top='+top+',screenX='+left+',screenY='+top+'');
			}
			
			function enableDropdown(){
				var categ = document.getElementById("category");
				var merken = document.getElementById("merk");
				var stijlen = document.getElementById("stijl");
				
				if(categ){
					if(categ.selectedIndex == 0){
			 			merken.disabled = true;
				 		stijlen.disabled = true;
		 			}				
				}
			}
			
			function initEventHandlers(){
				
				// ARS adresgegevens, popup
				var ars_beeld = document.getElementById('ars_beeld');
				if(ars_beeld){
					ars_beeld.onclick = function(){
						popUpWindow('http://www.arslochristi.com/info/imgs/ars-groot.jpg',0 ,0 , '345', '233')
					};
				}				
				// ARS catalogus overzicht, dropdowns
				var categ_dropdown = document.getElementById('category');
				if(categ_dropdown){
					categ_dropdown.onchange = function(){
						document.forms['categ_dropdown'].submit();
					}
				}
				// ARS catalogus overzicht, merken
				var merk_dropdown = document.getElementById('merk');
				if(merk_dropdown){
					merk_dropdown.onchange = function(){
						document.forms['merk_dropdown'].submit();
					}
				}
				// ARS catalogus overzicht, stijlen
				var stijl_dropdown = document.getElementById('stijl');
				if(stijl_dropdown){
					stijl_dropdown.onchange = function(){
						document.forms['stijl_dropdown'].submit();
					}
				}
				

			}
			
			window.onload = function (){
				initEventHandlers();
				enableDropdown();
				}