I'm sorry, you are correct, tooltips are supported. I have just run a quick example and i was able to add tooltips to the data points. Once you add the tooltip a tooltip tag should be created:
<tooltip></tooltip>
And you will just have to fill in the tooltip with the text that you want to display:
<tooltip>TEST</tooltip>
If the tooltip are still not working, please update to the latest version of DWC (1.0.3).