Gets the CustomItemContainerGenerator that creates the containers for the data items as well as the items located in the non-fixed header and footer sections of a grid, its groups, and its details.
Target Platforms: Windows 11, Windows, 10, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2