With GanttChartDataGrid, ScheduleChartDataGrid and other timeline-based components from DlhSoft Gantt Chart Light Library you, as a developer, can easily configure custom working (and therefore also nonworking) time, including by setting the limits of the week, e.g. WorkingWeekStart = Monday, and WorkingWeekFinish = Saturday, for example (besides also being able to set up WorkingDayStart/Finish time of days, and any specific nonworking intervals such as holidays or breaks).
Still, the component will also present (and gray out) the remaining nonworking days if you just let the default values for VisibleWeekStart/Finish properties (Sunday-Saturday).
Here we need to provide an important heads-up, though: you cannot control with those general settings what is the actual day for week starting, i.e. where the UI should to display vertical week separators simply because not always you would need to display weeks in the component, although working time can always be based on weeks.
Instead, if you want to have vertical separator lines between Sundays and Mondays (or between Fridays and Saturdays) rather than between Saturdays and Sundays, you will need to use another ScaleType value – “WeeksStartingMonday” on the Scale item that was previously set to type “Weeks” in the Scales collection of the component (or “WeeksStartingSaturday” if that’s more appropriate for your application users.)