private void TargetTextBox_DragOver(object sender, DragEventArgs e)
{
var point = e.GetPosition(TargetTextBox);
var range = TargetTextBox.Document.GetRangeFromPoint(point, Windows.UI.Text.PointOptions.ClientCoordinates);
TargetTextBox.Document.Selection.SetRange(range.StartPosition, range.EndPosition);
TargetTextBox.Focus(FocusState.Keyboard);
}
private void SetFocus_Click(object sender, RoutedEventArgs e)
{
TargetTextBox.Focus(FocusState.Programmatic);
}