How to embed web widgets into the dashboard.

We are filtering script tags and URLs for security reasons.

Does that mean the html viewlet will NEVER support javascript? If so, will there be another viewlet that supports javascript?

All viewlets contributed on the server have a lot of JavaScript (those are the viewlets that you can add from the chooser). Static HTML viewlet is there to quickly add static text and links but is not designed as an alternative to contributing viewlets server-side. It is extremely easy to do very nasty things to the dashboard from JS if allowed in the HTML viewlets.

In the future we will consider isolating the viewlet in its own iframe which would allow us to relax this restriction.