wpf - Why TabControl.SelectedContent != (TabControl.SelectedItem as TabItem).Content?

Question

The following sample shouldn't beep (in my opinion) but it does. Why? Does that mean the SelectedContent property is useless? Is it a bug in WPF?

<TabControl SelectionChanged="TabControl_SelectionChanged">
    <TabItem Header="Tab 1">
        <Grid/>
    </TabItem>
    <TabItem Header="Tab 2">
        <Grid/>
    </TabItem>
</TabControl>

 

void TabControl_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    var t = sender as TabControl;
    if (t.SelectedContent != (t.SelectedItem as TabItem).Content) Console.Beep();
}

Answer 1

I did some testing and found that the SelectedContent property is set after the SelectionChanged Event has been consumed, while the SelectedItem is set before the event is raised.!

Change one of the Grids to a Stackpanel and set a breakpoint on your if clause...