clicking on tag should hide all other tags in statemap rendering

[KodyKantor]

Sometimes the most important events are events that only occur for a few milliseconds. It can be very difficult to find these short events in a statemap without doing a lot of zooming, panning, changing coalescence values, or changing time boundaries.

To make this a little easier it would be great if we could simply click on a tag in the legend and have the statemap hide the deselected states in the statemap rendering. Optionally the user should be able to select more than one state to display, and deselect any currently selected state.