Public Event MouseLeftButtonDown As MouseButtonEventHandler

Dim instance As UXDataComboBoxCellBase
Dim handler As MouseButtonEventHandler
 
AddHandler instance.MouseLeftButtonDown, handler

public event MouseButtonEventHandler MouseLeftButtonDown

public event MouseLeftButtonDown: MouseButtonEventHandler; 

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

public: __event MouseButtonEventHandler* MouseLeftButtonDown

public:
event MouseButtonEventHandler^ MouseLeftButtonDown