How to get a WPF Toolbar to bind to a collection in my VM without using expander

I have a WPF window that has a ToolBar. I have a collection of objects in my VM that I'm binding to. They appear as buttons but they always get pushed to the expanded drop down part of the ToolBar. How do I make those buttons appear in the standard part of the ToolBar?

I have the following XAML:

<ToolBarTray Grid.Row="1">
    <ToolBar ItemsSource="{Binding Path=MyList}" >
        <ToolBar.ItemTemplate>
            <DataTemplate  >
                <Button ToolTip="{Binding ButtonName}" 
                        Command="{Binding Path=ButtonCommand}" >
                    <Button.Content>
                        <Image Width="32" Height="32" Source="{Binding ImageSource}"/>
                    </Button.Content>
                </Button>
            </DataTemplate>
        </ToolBar.ItemTemplate>
    </ToolBar>
</ToolBarTray>

I have the following C#:

public List<MyClass> MyList
    {
        get
        {
            return new List<MyClass>
                       {
                           new MyClass{ButtonName="Button1",ImageSource=@"C:\Projects\WpfApplication2\WpfApplication2\Employee.pn开发者_JAVA百科g"},
                           new MyClass{ButtonName="Button2",ImageSource=@"C:\Projects\WpfApplication2\WpfApplication2\Employee.png"},
                           new MyClass{ButtonName="Button3",ImageSource=@"C:\Projects\WpfApplication2\WpfApplication2\Employee.png"},
                           new MyClass{ButtonName="Button4",ImageSource=@"C:\Projects\WpfApplication2\WpfApplication2\Employee.png"},
                       };

        }
    }

This is the visual result:

There is a bug in the toolbar, if you re-size the window, the problem goes away.

The solution is using another control, like:

public class WorkaroundToolBar : ToolBar
{
    private delegate void IvalidateMeasureJob();

    public override void OnApplyTemplate()
    {
        Dispatcher.BeginInvoke(new IvalidateMeasureJob(InvalidateMeasure), 
                                     DispatcherPriority.Background, null);
        base.OnApplyTemplate();
    }
}

Check out this thread for more info

You can also set the height of the toolbar in the xaml to a reasonable value which has worked for me.

To add to Eduardo's, I had to slightly tweak this since my item source was getting populated asynchronously, some time after the initial UI is displayed:

public class ToolBar : System.Windows.Controls.ToolBar
{
    public override void OnApplyTemplate ()
    {
        Dispatcher.BeginInvoke ((Action)(InvalidateMeasure), DispatcherPriority.Background, null);
        base.OnApplyTemplate ();
    }
    protected override void OnItemsChanged (NotifyCollectionChangedEventArgs e)
    {
        base.OnItemsChanged (e);
        Dispatcher.BeginInvoke ((Action)(InvalidateMeasure), DispatcherPriority.Background, null);
    }
}

This was enough to catch all edge cases and have the overflow properly happen as needed after population of the items.