Dynamically updating a timeline is broken

Dynamically updating a timeline does not work with Vaadin 6.7.4 and timeline 1.2.3.

The test case http://dev.vaadin.com/browser/addons/Timeline/tests/com/vaadin/addon/timeline/tests/Monitor.java exhibits this problem across multiple browsers. The behavior is somewhat erratic: Changing the range with the selection bar does not adjust the graph, sometimes the graph is not painted at all.

If I change the code to add a fixed number of items upfront, then it works as expected.