An interesting idea... I'm assuming that this goes beyond just making sure that the cursor is not an hourglass but actually to synchronize some stuff that may be happening behind the scenes asynchronously for which there is no onscreen visible property to check?
A cool idea... and making it into a Keyword Operation Script extension I'm assuming, so it can show up in that list of operations/Checkpoints, yes?
I did something similar using the page loading indicator in Chrome. (Mainly due to DocumentReadyState status in Chrome being complete rubbish)
But I've never tried using the mouse to sync things. Nice idea, but given how quickly it can flash between statuses, I can see short changes being easily missed. Good if it works for you though.
