Hi Robin,
Thank you for using Syncfusion products.
Show context menu when right click on ToolStripGalleyBy default, RibbonControlAdv allows you to show the contextmenu when right clicking on the ToolStripGallery.
The following sample demonstrates the same.
http://websamples.syncfusion.com/samples/Tools.Windows/F74239/main.htmPlease let me know if I misunderstood your requirement.
Regards,
Jaya