Paint.NET :: Plugins To Interact Or Function Directly On Canvas / Layer

Is there some sort of restriction in Paint.NET that restricts the folks creating plugins from permitting the plugins to interact or function directly on the canvas/layer?

For instance the smudge and liquify (and others) open another window where you make your adjustments. The reason why I ask is this results in doing some things blindly because you can't see the rest of the canvas. I think some of these plugins will be so much more effective (especially with the recent addition of grid warping) if you can do some of these things on the canvas so you can shape images/textures to follow contours, but this is nearly impossible without doing so with several blind attempts.