Regarding Chrome, checkout the monitorEvents() via the command line API.
Open the console via Menu > Tools > JavaScript Console.
Enter monitorEvents(window);
View the console flooded with events
...
mousemove MouseEvent {dataTransfer: ...}
mouseout MouseEvent {dataTransfer: ...}
mouseover MouseEvent {dataTransfer: ...}
change Event {clipboardData: ...}
...
There are other examples in the documentation. I'm guessing this feature was added after the previous answer.