[marwis]

But this doesn't happen in native UIs. I think this is because JS event handlers are asynchronous and not running within native event loop.

[zyxin]

The way Windows handles it seems to be that hardware rendering of the pointer is turned off when you drag around windows. It was very obvious when I was using f.lux, the bright white pointer would turn yellow like the rest of the screen when dragging.

Maybe you could try turning the actual cursor invisible when dragging and instead render a custom drag cursor parented to the object being dragged.