Customising Contextual Ribbon Tabs In Visio 2010

I’ve recently been transferring some old VBA ShapeSheet utilities over to a c# add-in for Visio 2010 and hit a problem when trying to add some custom groups to the ShapeSheet Design ribbon tab.  Using Ribbon.xml, I was happily able to add groups to either custom tabs or built-in ones such as ‘Home’, but for love nor money couldn’t get anything to show in the ShapeSheet tab. 

Chris Hopkins, from the Visio team, kindly set me straight and the solution was in understanding that not all tabs are created equal and that the ShapeSheet Design tab belongs to a set called Contextual Tabs…