This is set from the rcWork member of MONITORINFOEX, to whit: "A RECT structure that specifies the work area rectangle of the display monitor that can be used by applications, expressed in virtual-screen coordinates. Windows uses this rectangle to maximize an application on the monitor. The rest of the area in rcMonitor contains system windows such as the task bar and side bars. Note that if the monitor is not the primary display monitor, some of the rectangle's coordinates may be negative values". The |rect| and |available_rect| properties are used to determine the available surface for rendering popup views.

public CefRectangle AvailableRectangle { get; set; }

public CefRectangle AvailableRectangle { get; set; }