public void BeginDrag(IDockDragSource dragSource)
 {
     this.DragSource = dragSource;
     if(!this.BeginDrag()){
         this.DragSource = null;
         return;
     }
     this.Outline = new DockOutline();
     this.Indicator = new DockIndicator(this);
     this.Indicator.Show(false);
     this.FloatOutlineBounds = this.DragSource.BeginDrag(this.StartMousePosition);
 }

            public void BeginDrag(IDockDragSource dragSource)
            {
                DragSource = dragSource;

                if (!BeginDrag())
                {
                    DragSource = null;
                    return;
                }

                Outline = new DockOutline();
                Indicator = new DockIndicator(this);
                Indicator.Show(false);

                FloatOutlineBounds = DragSource.BeginDrag(StartMousePosition);
            }

        internal void TestDrop(IDockDragSource dragSource, DockOutlineBase dockOutline)
        {
            if (VisibleNestedPanes.Count == 1)
            {
                DockPane pane = VisibleNestedPanes[0];
                if (!dragSource.CanDockTo(pane))
                    return;

                Point ptMouse = Control.MousePosition;
                uint lParam = Win32Helper.MakeLong(ptMouse.X, ptMouse.Y);
                if (!Win32Helper.IsRunningOnMono)
                    if (NativeMethods.SendMessage(Handle, (int)Win32.Msgs.WM_NCHITTEST, 0, lParam) == (uint)Win32.HitTest.HTCAPTION)
                        dockOutline.Show(VisibleNestedPanes[0], -1);
            }
        }

 internal void BeginDrag(IDockDragSource dragSource)
 {
     GetDockDragHandler().BeginDrag(dragSource);
 }

        internal void TestDrop(IDockDragSource dragSource, DockOutlineBase dockOutline)
        {
            if (!dragSource.CanDockTo(this))
                return;

            Point ptMouse = Control.MousePosition;

            HitTestResult hitTestResult = GetHitTest(ptMouse);
            if (hitTestResult.HitArea == HitTestArea.Caption)
                dockOutline.Show(this, -1);
            else if (hitTestResult.HitArea == HitTestArea.TabStrip && hitTestResult.Index != -1)
                dockOutline.Show(this, hitTestResult.Index);
        }

 internal void TestDrop(IDockDragSource dragSource, DockOutlineBase dockOutline)
 {
     if(this.VisibleNestedPanes.Count == 1){
         DockPane pane = this.VisibleNestedPanes[0];
         if(!dragSource.CanDockTo(pane)){
             return;
         }
         Point ptMouse = MousePosition;
         uint lParam = Win32Helper.MakeLong(ptMouse.X, ptMouse.Y);
         if(NativeMethods.SendMessage(this.Handle, (int)Msgs.WM_NCHITTEST, 0, lParam) == (uint)HitTest.HTCAPTION){
             dockOutline.Show(this.VisibleNestedPanes[0], -1);
         }
     }
 }

            public void BeginDrag(IDockDragSource dragSource)
            {
                DragSource = dragSource;

                if (!BeginDrag())
                {
                    DragSource = null;
                    return;
                }

                Outline = DockPanel.Theme.Extender.DockOutlineFactory.CreateDockOutline();
                Indicator = DockPanel.Theme.Extender.DockIndicatorFactory.CreateDockIndicator(this);
                Indicator.Show(false);

                FloatOutlineBounds = DragSource.BeginDrag(StartMousePosition);
            }