Hello,
The desired behavior can be achieved by setting the KeyboardNavigation.TabNavigation property of the RadRibbonView control to Cycle and also setting it to Continue for the child controls:
<telerik:RadRibbonView x:Name="radRibbon" ApplicationName="Tab Index Test" KeyboardNavigation.TabNavigation="Cycle">
<telerik:RadRibbonView.Items>
<telerik:RadRibbonTab Header="Test Tab" >
<telerik:RadRibbonGroup KeyboardNavigation.TabNavigation="Continue" >
<StackPanel>
<TextBox Width="50"/>
<TextBox Width="50"/>
</StackPanel>
</telerik:RadRibbonGroup>
<telerik:RadRibbonGroup KeyboardNavigation.TabNavigation="Continue" >
<StackPanel>
<TextBox Width="50" />
<TextBox Width="50" />
</StackPanel>
</telerik:RadRibbonGroup>
</telerik:RadRibbonTab>
</telerik:RadRibbonView.Items>
</telerik:RadRibbonView>
Regards,
Dilyan Traykov
Progress Telerik