function openWindow() {
    /* argumenten verzamelen */
	thePage 	= (arguments[0]!=null && arguments[0]!='') ? arguments[0] : null;
	theWidth 	= (arguments[1]!=null && arguments[1]!='') ? arguments[1] : null;
	theHeight 	= (arguments[2]!=null && arguments[2]!='') ? arguments[2] : null;
	theOptions 	= (arguments[3]!=null && arguments[3]!='') ? arguments[3] : null;
	theTitle	= (arguments[4]!=null && arguments[4]!='') ? 'popupWindow'+arguments[4] : 'popupWindow'; /* Ten behoeve van meerdere pop-up instances */

	theSpecs = "";
	if(theWidth!=null) theSpecs += "width="+theWidth;
	if(theHeight!=null){
		if(theSpecs.length>0) theSpecs += ",";
		theSpecs += "height="+theHeight;
	}
	if(theOptions!=null){
		if(theSpecs.length>0) theSpecs += ",";
		theSpecs += theOptions;
	}	
		
	popupWindow = window.open(thePage,theTitle,theSpecs);
	if(!popupWindow){
		alert('Wellicht heeft u een popup-blocker geïnstalleerd! Script gestopt!');
		return false;
	}/*else{
		history.go(-1);
	}*/
	if (window.focus){
		popupWindow.focus();
	}else{
		return false;
	}
	return true;
}