Question

base.event += this.EventHandler()

is this code safe ?
will it cause a leak ?

Answer 1

It’s better practice to override the method that fires the event, for example:

protected override OnClick(object sender,EventArgs e)
{
    base.OnClick(sender,e);

   // Your code here, or before the base call depending how you want it to operate
}

Of course if it doesn’t offer you this method (although it really should) you will have to stick to binding to the Event itself.