I get the first change, but what was the second one around the $viewport events even doing? Looks like some kind of workaround.

You mean this code var viewportEvents = $._data($viewport[0], "events"); ?
It's a trick that I found out while googling on how to know what events are registered, see this SO, this returns all events registered on that jQuery element that you provide as first argument.

In the code that I added, it basically does the following:

• check if the viewport element already has the mousewheel event handler associated
  • if Yes, then do nothing
  • if No, then add the mousewheel scroll handler

This avoids adding multiple event listeners for the same handler, which could be really bad and slow down the entire grid.

You might be wondering why am I doing that anyway? Because in my lib, we can add a freeze column at any point in time (see animated gif) and for that I use grid.setOptions({ frozenColumn: 2: enableMouseWheelScrollHandler: true }) to freeze at column 2 and when I remove it then I use the grid.setOptions({ frozenColumn: -1, enableMouseWheelScrollHandler: false }) which runs the 2nd piece of code that you were looking at... so basically dynamically adding the mousewheel scroll handler

OK, nice!

And you'll be wanting a release?

that would be nice too 😃