The Merge event handler receives an argument of the DevExpress.Xpf.Docking.BarMergeEventArgs type.
The Merge event fires when the merging mechanism is invoked.
Handle this event to perform additional bars/menus customization.
For instance, you can manually merge specific bars by calling the Bar.Merge method.
To undo customizations made via the Merge event, handle the DockLayoutManager.UnMerge event.