I used Swing overlay. I plan to rebuild using the Xith3D GUI library for performance reasons. Most of the components are customized anyway. I assume Xith3D GUI uses alpha transparencies.
Yeah sure. The Xith3D HUD is clean a structured code, so if you think there are improvements needed just go on and add what you need (and if you're not sure how to, just ask here and we'll discuss the best design/implementation).
I plan to use the HUD for a more extensive use but I won't describe here cause I'm just growing my vaporware reputation.