Define Custom Trigger Behavior

Updated on Mar 26, 2026

You can use a custom behavior that will perform additional logic when attaching the RadRadialMenu to the target element. You have to create a class that inherits from the RadialMenuTriggerBehavior class and override its methods to implement custom logic defining where and when the context menu will appear/diappears. The RadRadialMenu is attached/detached to the target element by calling the AttachToTargetElement/DetachToTargetElement method.

This example demonstrates how you can display the context menu when the text in a TextBox is changed and hide it when the Esc button is pressed.

First, create a class that inherits from the RadialMenuTriggerBehavior class. You can override its SubscribeToTargetEvents and UnsubscribeFromTargetEvents methods to implement your custom logic for triggering the appearance of the menu.

Example 1: Custom RadialMenuTriggerBehavior

XAML

public class CustomTriggerBehavior : RadialMenuTriggerBehavior
{
	public CustomTriggerBehavior()
	{
		this.AttachTriggers = RadialMenuAttachTriggers.None;
	}

	protected override void SubscribeToTargetEvents(FrameworkElement element)
	{
		base.SubscribeToTargetEvents(element);

		var textBox = element as TextBox;
		textBox.TextChanged += TextBoxTextChanged;
		textBox.KeyDown += TextBoxKeyDown;
	}

	void TextBoxKeyDown(object sender, KeyRoutedEventArgs e)
	{
		if (e.Key == VirtualKey.Escape)
		{
			this.DetachFromTargetElement();
		}
	}

	void TextBoxTextChanged(object sender, TextChangedEventArgs e)
	{
		this.AttachToTargetElement();
	}

	protected override void UnsubscribeFromTargetEvents(FrameworkElement element)
	{
		var textBox = element as TextBox;
		textBox.TextChanged -= TextBoxTextChanged;
		textBox.KeyDown -= TextBoxKeyDown;

		base.UnsubscribeFromTargetEvents(element);
	}
}

Then set the attached RadRadialContextMenu properties to the target element.

Example 2: Set the Behavior Property

XAML

<TextBox Width="200">
	<navigation:RadRadialContextMenu.Behavior>
		<local:CustomTriggerBehavior/>
	</navigation:RadRadialContextMenu.Behavior>
	<navigation:RadRadialContextMenu.Menu>
		<navigation:RadRadialMenu/>
	</navigation:RadRadialContextMenu.Menu>
</TextBox>

See Also

• RadRadialMenu as a Context Menu