Thank you for your help. I am facing a unique problem in this case. I am developing in C# WPF. I am using QuickAccessToolBar.RadRibbonDropDownButton item as I could not find QuickAccessToolBar.OverflowButtonElement and it is fine. If I use a simple RadRibbonView class for my Ribbon control and use DropDownOpened event as you suggested there is no problem. Everytime I click on the RadRibbonDropDownButton icon, the event is triggered and everything is perfect.
But the problem arises as I am using a class CustomRibbonView : RadRibbonView [CustomRibbonView is derived from RadRibbonView]. I HAVE NOT written any specific code for Quick Aceess Toolbar in this class [Am I missing a trick here?]. Now in the MainWindow.xaml.cs file in RibbonBar.Load event I have suscribed to DropDownOpened event. Please refer below:-
Now when the application is loaded for first time and I click on the RadRibbonDropDownButton icon in QAToolBar, ther suscribed event is fired and everything is fine. If I click on the first item i.e. "Show Below The Ribbon" and the toolbar goes below the ribbon as expected. But now if I click on the RadRibbonDropDownButton icon again, the event DropDownOpened is not fired and it is not fired anytime after.
Could not figure it out.