ARCed.UI.DockContentHandler.IDockDragSource C# (CSharp) Method

        Rectangle IDockDragSource.BeginDrag(Point ptMouse)
        {
            Size size;
            DockPane floatPane = this.FloatPane;
            if (this.DockState == DockState.Float || floatPane == null || floatPane.FloatWindow.NestedPanes.Count != 1)
                //size = DockPanel.DefaultFloatWindowSize;
                size = (this.Content as DockContent).DefaultFloatSize;
            else
                size = floatPane.FloatWindow.Size;

            Point location;
            Rectangle rectPane = this.Pane.ClientRectangle;
            if (this.DockState == DockState.Document)
            {
                if (this.Pane.DockPanel.DocumentTabStripLocation == DocumentTabStripLocation.Bottom)
                    location = new Point(rectPane.Left, rectPane.Bottom - size.Height);
                else
                    location = new Point(rectPane.Left, rectPane.Top);
            }
            else
            {
                location = new Point(rectPane.Left, rectPane.Bottom);
                location.Y -= size.Height;
            }
            location = this.Pane.PointToScreen(location);

            if (ptMouse.X > location.X + size.Width)
                location.X += ptMouse.X - (location.X + size.Width) + Measures.SplitterSize;

            return new Rectangle(location, size);
        }