QATToolbar settings within a workspace. 

All constructors take a parent argument and will add the created item to the parent.

Autodesk.AutoCAD.Customization.ElementBase
    Autodesk.AutoCAD.Customization.VersionableElement
        Autodesk.AutoCAD.Customization.CustomizationElement
            Autodesk.AutoCAD.Customization.WorkspaceQuickAccessToolbar

Public Class WorkspaceQuickAccessToolbar
Inherits CustomizationElement

public class WorkspaceQuickAccessToolbar : CustomizationElement;