#Tooltip showing Column's SortDirection#
This example demonstrates how to add a Tooltip for GridViewDataColumn's Header which shows its SortDirection.
See also:
WPF: http://docs.telerik.com/devtools/wpf/controls/radgridview/sorting/programmatic.html
SL: http://docs.telerik.com/devtools/silverlight/controls/radgridview/sorting/programmatic.html