When the ItemsSource of the control is populated from a background thread, users are not allowed to manually set the position of the horizontal splitter.

The DisplayMemberPath property is not respected

Workaround:
Use an implicit style targeting RadOutlookBarItem instead of the DisplayMemberPath property. You can define the style in the xaml page (the view) where the RadOutlookBar control is defined.

<Window.Resources>
    <Style TargetType="telerik:RadOutlookBarItem">
        <Setter Property="Header" Value="{Binding ItemHeader}" />
    </Style>
</Window.Resources>

Create integration example with TransitionControl.

Include the Show more/fewer and add/remove buttons functionality in the bottom menu.
Properties that get the ActiveItems' Count and MiniizedItems' Count also needed.

Easily customize the bottom menu with user defined RadMenu items.

When the OutlookBar is minimized and you click the right splitter without moving it. Then the outlookbar is still minimized does not expand to the previous expanded position

Implement Tab Navigation

Add minimize/restore animations

Add a property which changes the minimize button orientation.

When the selected item is Collapsed, the RadOutlookBar still displays its content and Title

There should be a way to swtich items and navigate the content easily using the keyboard only.

Implement "Add or Remove Buttons" functionality as in MS OutlookBar.
http://www.telerik.com/ClientsFiles/170274_fortelerik.jpg

Add StyleTypedProperty to MinimizedArea to aleviate editting the item container style of the MinimizedAreaItem.

Event when dragging the horizontal splitter

Add a section, separate from Content area

TabIndex/Tab navigation is not working inside OutlookBar.

Add Minimized and Restored event handlers in the OutlookBar

Allow customizing the Items position.

The selection of a minimized item cannot be visually cancelled.

RadPanelBar`s expand/collapse behavior needed in RadOutlookBar