Code

diagram.addEventListener(Events.createEditControl, onCreateEditor);

function onCreateEditor(sender, args)
{
	var select = document.createElement("select");

	var yes = document.createElement('option');
	yes.value = "Yes";
	yes.innerHTML = "Yes";
	select.appendChild(yes);
	var no = document.createElement('option');
	no.value = "No";
	no.innerHTML = "No";
	select.appendChild(no);

	args.setControl(select);

	var bounds = args.getBounds();
	select.style.position = 'absolute';
	select.style.left = bounds.x + 'px';
	select.style.top = bounds.y + 'px';
	select.style.width = bounds.width + 'px';
	select.style.height = bounds.height + 'px';
	select.style.zIndex = 2;

	document.body.appendChild(select);
}