Comment 41 for bug 728643

> Having a client-side daemon that does the job is racy since some events will be
> sent before the client gets a chance to deactivate the events.

Thinking about this idea some more: What if the client-side daemon was actively sending fake scroll events to the window, rather than just passively waiting for the right moment to tell the driver to deactivate a stream of real events?

Then the only effect of losing the race would be that some extra scroll events get sent to the original window with the original modifier state, rather than to whatever window is now under the pointer with the current modifier state.