The column footers can be used to display aggregated information about the data in the column via aggregate functions. The aggregate functions might be found in the Telerik.Windows.Data assembly.
The available functions are:
AverageFunction – returns the average of the values in the column.
CountFunction – returns the number of all items in the column.
FirstFunction – returns the first element in the column according to the current sorting.
LastFunction – returns the last elements in the column according to the current sorting.
MaxFunction – returns the Max of the values in the column.
MinFunction – returns the Min of the values in the column.
SumFunction – returns the Sum of all values in the column.
To display an aggregate function for a certain column, just instantiate the function you need and add it to the AggregateFunctions collection of that column.
As the RadTreeListView directly inherits the RadGridView it uses its filtering mechanism. To learn more read the respective topic in the RadGridView's documentation.