What I meant is an advanced mask tool which moves the mask and optionally (rotation, perspective, scaling) the underlying image along with it then you have what you call pixel tracking. With this tool you can achieve fanatical effects, like color correction applied only on a mask and only on an object. Even though the object is moving, you can do a color correction and make the background in a completely different color, and on top of that another layer. I would have liked to have this tool when I made the short video for Cinelerra. That's why I don't think we should program these two things like mask tracking and pixel tracking completely separate from each other. I think we could do that in one tool.

With all my respects Sam, but the mask tool is not the right one in this case. The skins tool is used to cut, but not to deform a video clip or image.
The ideal complement to a pixel tracking tool is perspective.
I do not know programming, but perspective has four points very defined by coordinates. Perhaps you could keep track of the four corner points on the screen and then assign the coordinates of each of these 4 points to the perspective points.
The mask could be used to make rounded corners of the video clip you have on the screen, or to trim a finger on top of it.
Normally these works are done frame by frame, it is the way that guarantees a perfect finish.