Public Event MouseRightButtonDown As MouseButtonEventHandler

Dim instance As UXRibbonDropDownButton
Dim handler As MouseButtonEventHandler
 
AddHandler instance.MouseRightButtonDown, handler

public event MouseButtonEventHandler MouseRightButtonDown

public event MouseRightButtonDown: MouseButtonEventHandler; 

In JScript, you can handle the events defined by another class, but you cannot define your own.

public: __event MouseButtonEventHandler* MouseRightButtonDown

public:
event MouseButtonEventHandler^ MouseRightButtonDown