Key frame animation screen

We need a screen to allow the user to create, edit, and delete key frames for a video clip, global filter, or transition. I am imagining a separate screen, instead of just having the main timeline incorporate this functionality. This new screen should have a preview video window (that previews the entire timeline between the IN and OUT of the current item). Adjusting a key frame, should rebuild the Westley XML and reload the video preview. Let's keep version 1 of this screen very simple. In other words, 1) list the properties, 2) Easily add a key-frame 3) list the key-frames in an editable-GtkTree.

The initial properties that can be set via a key-frame are the following:

TRANSITIONS
1) Geometry - X, Y, Height, Width, Alpha
2) Luma - Softness
3) Audio Mixing - Volume

FILTERS
1) brightness