private void TabControlExt_TabOrderChanging(object sender, Syncfusion.Windows.Tools.Controls.TabOrderChangingEventArgs e)
 {
     // Restrict the Tab order changing
     e.Cancel = true;
     var draggeditem = e.TargetItem;
     var oldIndex    = e.OldIndex;
     var newIndex    = e.NewIndex;
 }
 private void dockingmanager1_TabOrderChanging(object sender, Syncfusion.Windows.Tools.Controls.TabOrderChangingEventArgs e)
 {
     // Restrict the Tab item order changing
     e.Cancel = true;
 }