This adds a new command /dtchatevent that labels events in the chat frames with a clickable link that pops open a tooltip describing the event that caused the line.
If anyone wants to check it out and provide feedback, here's the place to do it.
So far I have the following things to add:
* Clicking on the currently open line should close the tooltip.
* Add a configuration for how large an event ring to keep (presently it's 1,000 events)
* Better messaging if you click on an event that's rolled out of the event ring.