This is the animator screen. The animation system lets you do keyframed forward kinematic animation of rigid body models. The animator lets you set the rotation of limbs by clicking and dragging. It can also insert, delete, and copy keyframes, and play and loop the animation you're editing. A single click takes to you the modeler, allowing you to easily switch from tweaking the animation to tweaking the model, and back.
The system was originally developed back in 2000 for CAVEMAN v1.x. CAVEMAN has a requirement to draw a large number of unique high poly animated characters onscreen at once. Many more than I've ever seen done with skinned meshes. Back in 2000, the original system could handle 50 characters on screen at once in combat with no real slowdowns on a baseline PC. With today's PCs, i'm shooting for at least 100-200 at once, maybe more. I've already tested over 100 at once with no problems on a baseline windows 7 PC (Compaq CQ2014 AMD dualcore E300 w/ onboard graphics chip only). Recently, i checked into adding IK capabilities, and have come up with a simple IK solver algo that I may add to the animator.