This is a beta version of a perspective transformation plugin. Unfortunately, I can't seem to post images using my flickr account (I get the message, "You are not allowed to use that image extension on this community.")  The plugin uses four double-vector controls to place the transformation control points. Due to CodeLab restrictions, the double vectors are all initially at the center of the window, and have to be moved to reasonable positions to produce a picture. It's not too hard to do, but