The logic of the IsContentPreserved (inherited from RadTabControl) property could be implemented in RadOutlookBar

Allow the user to manually set the position of the OutlookBarItem : ActiveArea, MinimizedArea or OverflowArea

Provide visibility enumeration for the Overflow button "WhenNeeded", "Visible", "Hidden/Collapsed"

The IsMinimizedChanged method does not inspect the ACTUAL width of the control

Event when dragging the horizontal splitter

Add Minimized and Restored event handlers in the OutlookBar

The selection of a minimized item cannot be visually cancelled.

Allow customizing the Items position.

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.

OutlookBar: Visual state of selected items in not correct

The ActiveItemsCount is not working

The control is not translated in German

Reason for declination: 
The XAML team has recently reviewed this issue and it cannot be reproduced by following the described steps in our help:
http://docs.telerik.com/devtools/silverlight/common-localization.html#localization-using-built-in-resources
If you still encounter this issue and it is blocking for your work please contact us through the support ticketing system with details on your setup and a reference to this item. 

Available in LIB version 2017.3.1113, it will be also available in the R1 2018 Release.

Implement Tab Navigation

Add minimize/restore animations

Add the posibilty for the RadOutlookBar control to have Width less than the specified MinWidth, when Minimized.

Content is lost when setting IsMinimizable to false and the OutlookBar is minimized

RadPanelBar`s expand/collapse behavior needed in RadOutlookBar

The style of the items that are contained in the dropdown content of the overflow button cannot be edited.

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.