function disableButtons() {
//disables all buttons on screen, so that the form can't be submitted twice
	for (var i=0;i<document.forms.length;i++) {
		var df = document.forms[i];
		for (var j=0;j<df.elements.length;j++) {
			if (df.elements[j].type) {
				if (df.elements[j].type == "submit" 
					|| df.elements[j].type == "button"
					|| df.elements[j].type == "reset"
					|| df.elements[j].type == "image") {
					//alert("disable " + df.elements[j].name);
					df.elements[j].disabled = true;
				}
			}
		}
	}
//	alert("buttons disabled");
}

function enableButtons() {
//re-enables all buttons on screen, gets called e.g. when a search result frame returns
//and the buttons on the search criteria screen can be enabled again
	for (var i=0;i<document.forms.length;i++) {
		var df = document.forms[i];
		for (var j=0;j<df.elements.length;j++) {
			if (df.elements[j].type) {
				if (df.elements[j].type == "submit" 
					|| df.elements[j].type == "button"
					|| df.elements[j].type == "reset"
					|| df.elements[j].type == "image") {
//					alert("enable " + df.elements[j].name);
					df.elements[j].disabled = false;
				}
			}
		}
	}
//alert("buttons enabled");
}