private void OnDockspaceSeparatorMoveRect(object sender, SplitterMoveRectMenuArgs e)
        {
            // Cast to correct type and grab associated dockspace element
            KryptonDockspaceSeparator separatorControl = (KryptonDockspaceSeparator)sender;
            KryptonDockingDockspace   dockspaceElement = _lookupSeparator[separatorControl];

            // Events are generated from the parent docking manager
            KryptonDockingManager dockingManager = DockingManager;

            if (dockingManager != null)
            {
                // Allow the movement rectangle to be modified by event handlers
                DockspaceSeparatorResizeEventArgs dockspaceResizeRectArgs = new DockspaceSeparatorResizeEventArgs(separatorControl, dockspaceElement, FindMovementRect(dockspaceElement, e.MoveRect));
                dockingManager.RaiseDockspaceSeparatorResize(dockspaceResizeRectArgs);
                e.MoveRect = dockspaceResizeRectArgs.ResizeRect;
            }

            KryptonDockingControl c = GetParentType(typeof(KryptonDockingControl)) as KryptonDockingControl;

            if (c != null)
            {
                // Inform our owning control that an update is starting, this will prevent drawing of the control area
                c.PropogateAction(DockingPropogateAction.StartUpdate, (string[])null);
                _update = true;
            }
        }