Office ribbon gallery control: How to achieve grouped items

Question

I'm now developing an add-in targeting PowerPoint 2010 and 2013. According to this MSDN page , gallery has only item and button as children, and all tutorials I could find online were involving only these 2 children. However, some galleries in Office were grouped up:

My question is: how to achieve this grouping?

Thanks a lot!

---

I have tried using a menu to wrap up a menu separator and a gallery, but the gallery shows like a drop down button, instead of an expected in-menu gallery:

Ps Below is what a typical gallery looks like:

Answer 1

As far as I know this is not possible.

There are quite a few things like this in the Office ribbon: you can see that it can be done since the official Office ribbon has it, but there is no way to do it when developing. Two examples are the one you posted and in ribbon gallery (like the Chart styles in Excel).

Here is an similar question answered by one of the authors of the RibbonX book: http://www.excelguru.ca/forums/showthread.php?612-Menu-containing-galleries-and-menu-separators