Starting with 2011 Volume 2 of Ultimate UI for Windows Forms, the grid filtering functionality works the same as the filtering behavior of Microsoft Excel®. Excel filters the list of cell values to only include the values that have not been filtered out by other columns.
The filtering functionality is provided by the WinGridFilterUIProvider™ component. Previous versions of the WinGridFilterUIProvider left all values in the drop-down tree, regardless of their filtered out status. For backward capability with the old functionality, a new property named OperandListFilterBehavior is now available on the UltraGridFilterUIProvider.