Thank you for the update.
In this case I would like to request ability to add items from System Menu to Quick Access as well.
The requested requirement relates to Office 2007 ribbon theme and it is the only theme which has Application Menu and all the other new themes has BackStage implementation. Since it is a very old and considering the theme as classic, we do not have any immediate plans to implement it, so we suggest you use newer themes which has BackStage implementation.
Please let us if you have any concern.
Also how to remove QuickItems group from customize quick access window?
Based on your update we understood your requirement is to totally remove the Customize QuickAcces Window from RibbonControlAdv, your requirement can be achieved with the Ribbon property “EnableQATCustomization”, set this to property to false to totally remove the option to customize the QAT.
Please find the code snippet below
this.ribbonControlAdv1.EnableQATCustomization = false;
We have prepared a sample for your reference.
Please let us know if this suits your requirement or revert us if we misunderstood your requirement.