I got split-screen editing working in Maud. I can work on two models at once or, as shown here, I can work with two different views of the same model. The 3-D view on the right side renders the model at a particular instant. The 2-D view on the left plots significant keyframes (in the selected bone, its ancestors, and its children) against time.
Maud is now at a point where I'd appreciate some constructive feedback. Later today I'll post a call for volunteers (alpha testers) on the Forum.