Hi Jeff,
Thanks for the sample. There are a couple things to point out:
1) You were using MaxWidth for the RibbonGallery but that is bad. Our RibbonGallery auto-sizes based on its current variant size and the size of its items. So instead of MaxWidth to constrain the gallery, use this sort of code:
gallery.MediumVariantColumnCount = 3;
gallery.LargeVariantColumnCount = 10;
gallery.VariantBehavior = RibbonGalleryVariantBehavior.NoCollapseNoAutoSize;
Then you'll have a really slick effect where as you make the window wider, it will grow and show more items as they fit. The VariantBehavior setting above prevents it from growing to infinity. You may want to change that option so that it does grow and use all available space. But see the documentation for more information on how the various variants for RibbonGallery behave. You really can do a lot with them when combined with other groups.
2) Your other question in the email was, how can you get items to show better in the drop-down. In your XAML you had put a ribbon:Menu where you should have placed a ribbon:PopupGallery in the RibbonGallery.PopupContent.
If you swap this code in the PopupContent, it looks great (there is code like this in our demos too so you may want to look at those):
<ribbon:PopupGallery InitialColumnCount="4"
ItemTemplate="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type ribbon:RibbonGallery}}, Path=ItemTemplate}"
ItemsSource="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type ribbon:RibbonGallery}}, Path=ItemsSource}"
/>
