The most common way to customize the appearance of items in Scheduling for WPF is by setting various properties in Calendar.ItemSettings. This would affect the appearance of all items in the control. For example ItemsVisible specifies whether to display the items, Size and HeaderSize define the dimensions of the item and its header and so on. Four properties in the ItemSettings class are particularly interesting - CalendarStyle, SelectedItemStyle, PointedItemStyle and PointedSelectedItemStyle. These properties define various aspects in the visualization of the items depending on their current state - normal, selected, hovered with the mouse and selected and hovered at the same time. For example SelectedItemStyle defines settings for items which are selected but not hovered with the mouse.
For more information on the item styles and how to assign specific styles to individual items, see Customizing the Item Styles.
