Defines the number of pixels that must be discounted from Screen's horizontal resolution (E3 Viewer's working area). Default value of this property is -1 (minus one), which assumes E3 Viewer's window configuration (with or without a title bar, with or without a border) together with the current computer's configuration (Windows-defined border width and title bar). This property cannot be changed at run time, even if E3 Viewer is inactive.