I placed a clipper into my design and I'm seeing two different problems with it's behavior. First, after it runs for a while the entire image shifts to the right and wraps around by maybe 16 pixels. I don't know if the clipper specifically is shifting the image or if its output is somehow confusing something downstream. The problem is definitely the clipper though as this defect does not occur when the clipper isn't in the system.
The second problem is that the clipper seems to have minimum limits after which it stops clipping correctly. We have a 1080i signal going through the DI to produce 1080p. I have the clipper setup for window mode and I've set it up to clip from 0,0 and cut out a 1920x1080 image. (i.e. No clipping by default.) As I begin to reduce either the height or the width eventually I encounter a point where instead of shaving a pixel off the end or a line of the bottom the result chops off huge chunks of the video and replaces it with whatever the last pixel is. For example, if the clip height is 800 then it works but at 799 I only get 200 lines of active video with the other 599 a solid color, most likely the value of the last pixel in line 200. Changing the width does the same thing, although at a different point. I have not done enough testing to know if the threshold of misbehavior moves with each build.