Background of Gantt Chart area within Gantt Chart Library and Project Management Library for WPF

How can we set the background of the Gantt Chart area of the components within Gantt Chart Library for WPF or Project Management Library for WPF?

You should set the WorkingTimeBackground and NonworkingTimeBackground properties of the control, representing the brushes to use for paiting the working and nonworking time intervals within the Gantt Chart area.