Back in the late 80's I ran a utility called DropShadow on my Amiga. It had a feature where it would draw progressively larger shadows for the frontmost windows. If the lowest window had a shadow of one pixel, the next lowest would have a shadow of two pixels. It also would reduce the size of the shadow when it fell on another window, depending on the depth of that window. For example, the section of the shadow of a window falling on a window two layers lower would be reduced by two pixels. I think it would be great if WindowFX could do this.