- Type: margin string
- Controls the amount of chrome that should be visible on each side of the window. The specified string should contain four numbers, separated by commas, indicating the margin in pixels for the top, right, bottom, and left edges of the window, respectively. This value may be -1 to use the default margin for that side on the current platform, 0 to have no system border (that is, to extend the client area to the edge of the window), or a value greater than zero to indicate how much less than the default default width you wish the margin on that side to be. If this value turns out to be less than 0, 0 is used.