I ran across an interesting KB article today.  I had never seen the "::" notation in JavaScript before, but here it is:

function ctrl::ClickEvent(a,b)
{
   alert("MyWindowControl_ClickEvent");
}

This function will handle the "ClickEvent" .NET event that is exposed to script through an object tag:

    <OBJECT id="ctrl" classid="YourDllName.dll#ActiveXSourcing.MyWindowControl">
    </OBJECT>

For more, read KB313891