Implicit style doesn't apply on RadRibbonTabs which are added via PRISM. 

UPDATE: An implicit style can not be applied on derived controls as their TargetType is different than the one defined in the implicit style. Basically if you set the style implicitly, the style is applied only on the types that match the TargetType exactly and not on elements derived from the TargetType value. You can find more information on the topic in the remarks section of the Style property definition: http://msdn.microsoft.com/en-us/library/system.windows.style%28VS.95%29.aspx

This is why in order to apply a Telerik predefined style on a UserControl deriving from RadRibbonTab, you  need to add a Style targeting the UserControl type in the Resources of the application. It is best to define that style after merging the Telerik ResourseDictionaries so that you can base the UserControl Style on the predefined "RadRibbonTabStyle".

When the ItemTemplateSelector property is used the class which inherits the DataTemplateSelector is never called.

RadRibbonGallery is compressed (collapsed). When you expand it with mouse a small popup appears near the Title of the application or to the right of the expanded RadRibbonGallery.

When the Windows OS theme is changed to Classic under Windows 7, the Minimize, Maximize and the Close button of the RadRibbonWindow disappear and the title bar becomes black.

Also note that when the theme is Classic and you start the application the window is displayed correct, but when you change the theme to Aero, the RadRibbonWindow style it is not changed

When you open the drop down button of the QuickAccessToolbar and then mouse over its drop down content, the "Customize Quick Access Toolbar" tool tip is displayed. This tool tip should be displayed only when the button is hovered

The HeaderStringFormat property is not bound in the default template of the control.

When you have a RibbonView in a RibbonWindow and you open another RibbonWindow from the first one, the paths of the minimize, maximize and close buttons of the first window disappears. Note that in order to reproduce this issue the Windows theme should be set to classic and the project should be started without debugging (Ctrl + F5)

The RibbonGroup Header is not displayed in data-bound scenario when HierarchicalDataTemplates are used.

The ApplicationMenu is displayed on the wrong monitor when hosted in RibbonWindow and the IsWindowsThemeEnabled is set to false.

The BorderBrush property of the RadToggleButton that is used inside the RadRibbonComboBox should be TemplateBound to the BorderBrush of the RadRibbonComboBox. By doing so clients will be allowed to change the BorderBrush for both text area and toggle button parts.

Available in LIB version: 2016.2.516

The RadRibbonView does not display in the designer when IsMinimized property is set to True.

When the RibbonWindow contains WindowFormsHost element with WinForms controls and the window is resized (for example with the Maximize/Restore Down buttons), the resizing is slow.

Note: The issue is reproducible only if the  RadRibbonWindow.IsWindowsThemeEnabled static property is set to False

RibbonSplitButton have different width in its dissable state compared to its normal state.

The fix is available in Q1 2015 SP Release.

RibbonWindow Title is displayer on multiple lines when its value is set to a very long string and used on Windows7(Aero).

The QAT is placed too close to the ribbon when hosted in a RadRibbonWindow.

In MVVM scenario, DropDownContent of the RibbonDropDownButton is databound.

In the DropDownContentTemplate, there is a RadContextMenu with menu items with Commands. These Commands do not fire. This has worked till Q2 2014.

The HeaderStringFormat property of the RadRibbonBackstageItem is not working [RadRibbonView]

The tab strip of the control is still visible when all tabs and the application button are collapsed in the Expression_Dark theme. HeaderVisibility of the RadRibbonTabs and the ApplicationButtonVisibility of the RadRibbonView are set to Collapsed.



Available in LIB version: 2016.2.601

When NoXaml binaries are used and there is content hosted in the RadRibbonWindow it gets clipped.

Available in LIB version: 2014.3.1312