wpf-devexpress-dot-xpf-dot-docking-dot-docklayoutmanager-d74643e2.md
Fires when a docking operation starts, and allows you to prevent this operation.
Namespace : DevExpress.Xpf.Docking
Assembly : DevExpress.Xpf.Docking.v25.2.dll
NuGet Package : DevExpress.Wpf.Docking
public event DockItemCancelEventHandler DockItemStartDocking
Public Event DockItemStartDocking As DockItemCancelEventHandler
The DockItemStartDocking event's data class is ItemCancelEventArgs. The following properties provide information specific to this event:
| Property | Description |
|---|---|
| Cancel | Gets or sets whether the current operation must be canceled. |
| Handled | Gets or sets a value that indicates the present state of the event handling for a routed event as it travels the route. Inherited from RoutedEventArgs. |
| Item | Gets the currently processed item. Inherited from ItemEventArgs. |
| OriginalSource | Gets the original reporting source as determined by pure hit testing, before any possible Source adjustment by a parent class. Inherited from RoutedEventArgs. |
| RoutedEvent | Gets or sets the RoutedEvent associated with this RoutedEventArgs instance. Inherited from RoutedEventArgs. |
| Source | Gets or sets a reference to the object that raised the event. Inherited from RoutedEventArgs. |
The event data class exposes the following methods:
| Method | Description |
|---|---|
| InvokeEventHandler(Delegate, Object) | When overridden in a derived class, provides a way to invoke event handlers in a type-specific way, which can increase efficiency over the base implementation. Inherited from RoutedEventArgs. |
| OnSetSource(Object) | When overridden in a derived class, provides a notification callback entry point whenever the value of the Source property of an instance changes. Inherited from RoutedEventArgs. |
End-users can perform docking operations by pressing a dock panel’s caption with the mouse and dragging it. Once a docking operation starts, the DockItemStartDocking event fires. To prevent panels from being docked, handle the DockItemStartDocking event and set the event’s Cancel parameter to true.
It’s also possible to prevent a dock item from being docked by setting the BaseLayoutItem.AllowDock property to false.
See Also