DataGrid.ColumnHeaderDragStarted Event
Occurs when the user begins dragging a column header using the mouse.
Namespace: System.Windows.Controls
Assembly: System.Windows.Controls.Data (in System.Windows.Controls.Data.dll)
Users can change the column order by dragging column headers only if the CanUserReorderColumns property is true.
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.