This option determines the way window shadows are displayed. It may have one of the following four values:

None:   When this setting is used, shadows are not displayed.
Dim: This setting displays a one-character border around the right and bottom edges of the window. This border displays the underlying data in low-intensity with a white foreground and a black background; in effect, the border is translucent. This border looks best when the shadowed window and the window it overlays do not both have black backgrounds.
Black: This setting displays a black border on the right and bottom edges of the window. On the right edge, this border is one character wide. On the bottom edge, the border is one-half character high. This gives a fairly uniform appearance to the border. The border depends on the existence of an "upper-half" block character on the display device. For machines that use a terminal database file, this character should be specified as the 12th character in the GM code in the terminal database file (GM defines the various graphics characters). Also, we recommend that you specify a "lower-half" character as the 13th GM character. If such characters do not exist, then the bottom border is a full character high. The Black setting is the default shadow style.
Lines: This setting causes the right and bottom edges to be shown with a border made from the line drawing set. This setting is not as appealing as the Dim or Black settings when color or reverse-video backgrounds are being used. When the background is black, however, this setting is preferable to the other two.

The configuration variable SCRN_SHADOW_STYLE is also supported.