Events.md

layout	post
title	Events — TabbedWindow | Syncfusion®
description	Key events and example handlers for `TabbedWindow`.
platform	WPF
control	TabbedWindow
documentation	ug

Events

This page lists the events raised by TabbedWindow / SfTabControl and gives small, named-handler examples to explain the events.

NewTabRequested

Raised when the user invokes the new‑tab action (new‑tab button) or when the app programmatically requests a new tab. Handle this event to supply the initial SfTabItem or to cancel creation.

Common event-args properties:

• Item — the SfTabItem or view model that will be inserted; assign this to provide default content.

{% tabs %} {% highlight C# %}

MainTabControl.NewTabRequested += MainTabControl_NewTabRequested;

private void MainTabControl_NewTabRequested(object sender, NewTabRequestedEventArgs e) { e.Item = new SfTabItem { Header = "Untitled", Content = new TextBlock { Text = "New" } }; } {% endhighlight %} {% endtabs %}

PreviewTabMerge

Raised before an incoming tab is merged into a target SfTabControl (for example when a tab is dropped from another window or tab control). Use this event to validate, transform, or reject incoming tabs.

Event-args properties:

• ResultingItem — the tab item as it would appear after the merge.
• DraggedItem — get the original dragged tab item.
• SourceControl — get the originating SfTabControl.
• TargetControl — get the receiving SfTabControl.
• Allow (bool) — set to false to reject the merge.

{% tabs %} {% highlight C# %}

MainTabControl.PreviewTabMerge += MainTabControl_PreviewTabMerge;

private void MainTabControl_PreviewTabMerge(object sender, TabMergePreviewEventArgs e) { e.Allow = true; if (!(e.ResultingItem is SfTabItem)) { e.ResultingItem = new SfTabItem { Header = "NewTab", Content = "NewContent" }; } } {% endhighlight %} {% endtabs %}

N> If the source and target tab item types are different, the PreviewTabMerge event allows us to replace the resulting item with a compatible type as per our convenience.