Camera Parallax Question

[Imma Cylon]

So, I'm VERY new to WallPaper Engine. . . In the editor I am trying to create a wallpaper with an "edge scrolling" effect. I have that part figured out. I changed all my setting in the "camera parallax" settings. . . How do I make the grid match my monitors aspect ratio instead of the aspect ratio of the image so that I can set my "Parallax Depth" and it be accurately displayed by "Camera Preview". . . Right now the mouse is over influencing, beyond the edge of my screen and moves into a black area. How do I get the camera parallax to stop at the edge of the image despite the mouse influence?

I hope this makes sense. . . Please help!