public Window1()
{
InitializeComponent();
// "tb" is a TextBox
DataObject.AddPastingHandler(tb, new DataObjectPastingEventHandler(OnPaste));
}
private void OnPaste(object sender, DataObjectPastingEventArgs e)
{
var isText = e.SourceDataObject.GetDataPresent(System.Windows.DataFormats.Text, true);
if (!isText) return;
var text = e.SourceDataObject.GetData(DataFormats.Text) as string;
}