Stores the default top edge position of the Preview Window dialog box when it was last used. This value will change if the dialog box is resized or moved and will be recalled when the dialog box is subsequently opened. The specified number provides the location of the top edge of the window from the top of the screen.
To help you visualize this, the image below has two rectangles, an orange rectangle that represents your screen dimensions, and a green rectangle that represents the position of the Preview Window dialog box.
This setting controls the distance between the top edge of the screen (B) and the top side of the window (E).
Entry Name: PreviewWindowPositionTop
Entry Type: Whole number that specifies the pixels from top of screen. The default value is 0.