About a year ago Kelly Linden debuted HTML HUD’s. See: #SL Server Update Week 34 for my first mention of HTML HUD’s in 2011. We have not seen many of these being used. The advantage of HTML HUD’s the reduction in scripts and prims needed to make a working interface.
Darien Caldwell is one of the creative types making such HUD’s. He has pointed out that these JIRA’s are a problem:
VWR-29448 – HTML (Shared Media) HUD objects exhibit Unintuitive Focus and Control Behavior. This is about how the HUD’s work and look within the viewer. Most floated in the viewer go transparent when they lose focus. We know that we have to shift focus to the panel, by clicking it, before we can click buttons in the Panel. HTML HUD’s do not go transparent when losing focus. This means we click buttons in them, probably expecting something to happen, and nothing happens. That nothing is deceiving. The first click shifts focus. A second click will activate the button.