Isso é " Galeria " controle, especificamente um < href="http://msdn.microsoft.com/en-us/library/dd940501(VS.85).aspx"> InRibbonGallery .
XML de exemplo:
<Group CommandName="cmdInRibbonGalleryGroup" SizeDefinition="OneInRibbonGallery">
<InRibbonGallery CommandName="cmdInRibbonGallery"
MaxColumns="10"
MaxColumnsMedium="5"
MinColumnsLarge="5"
MinColumnsMedium="3"
Type="Items">
<InRibbonGallery.MenuLayout>
<VerticalMenuLayout Rows="2"
Gripper="Vertical"/>
</InRibbonGallery.MenuLayout>
<InRibbonGallery.MenuGroups>
<MenuGroup>
<Button CommandName="cmdButton1"></Button>
<Button CommandName="cmdButton2"></Button>
</MenuGroup>
<MenuGroup>
<Button CommandName="cmdButton3"></Button>
</MenuGroup>
</InRibbonGallery.MenuGroups>
</InRibbonGallery>
</Group>