The buttons of the RadRibbonWindow are not visible in Office2013. The fill of the paths is the same color as the background.

RibbonView in SL throws exception when LocalizationManager.UseDynamicLocalization is set to true

If you set the Visibility of a RadRibbonTab hosted in a ContextualGroup to Collapsed, a placeholder is visualized, when it shouldn't.

Add DataBinding Supoort for Contextual Groups / Tabs

Edited Style of the ScreenTip does not apply when the ScreenTip is set as attached property.
Also, when you create a CustomControl deriving from the ScreenTip control, its default style is not applied.

When a style is applied on the QAT, changing its position opens its popup menu unexpectedly. The style doesn't have to be customized, the issue is reproducable with the default OfficeBlack style of the control.

When you set the Content and the Image properties of the RadGalleryItem, they get on top of each other.

When UserControls are dynamically added in the RibbonView Items collection, they are displayed as RibbonTab Headers. Instead they should create a RibbonTab collection where each control represents the content of a RibbonTab.

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".

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".

Expose a property to control the visibility of the background behind the RibbonTab.Headers

UPDATE: The RadRibbonView's Background property can be used to set a color behind the RadRibbonTabs

NullReferenceException design-time exception is thrown in VS designer when the RadRibbonTab is defined as a root element of a UserControl.

System.InvalidOperationException is thrown in the VS designer in a view defining a RadRibbontab control.

When a view doesn't specify DesignHeight/Width, the RibbonView throws design-time exception if it contains ContextualGroups.

Text improperly aligned for all RibbonView buttons

In Windows8 theme, the selected Contextual RibbonTab has an inner border which has to be removed to indicate the selection properly.