This WPF Outlook bar mimics that of the Outlook 2007/2010 navigation bar. 

Control that matches the presentation of Outlook 2007/2010 navigation bar.
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Users can at any time collapse the xamOutlookBar so that it retracts to a vertical bar, yielding maximum space to your application.
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Maximize the space in your application by collapsing the Outlook bar. 
Information that exceeds the dedicated space can be retrieved from an icon using the WPF Outlook bar dynamic overflow feature. 

When groups exceed the space available to them in the Outlook group bar, the UI can compress to a small icon.
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Users can govern how much space the xamOutlookBar's selected group content receives by using the group area splitter bar dividing the selected group content from the groups presenter.
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Split selected content using the WPF Outlook bar splitter separator feature.