Uses of MouseRegion should not be affected at all.

If your code directly uses RenderMouseRegion or
MouseTrackerAnnotation, be aware that onExit
is now called when the exit is caused by events that used
to call MouseTracker.detachAnnotation.
This should not be a problem if no states are involved,
otherwise you might want to add the mounted-exit check,
especially if the callback is leaked so that outer
widgets might call setState in it. For example:

Code before migration:

class

MyMouseRegion

extends

SingleChildRenderObjectWidget

const

MyMouseRegion

({

this

onHoverChange

});

final

ValueChanged

bool

onHoverChange

@override

RenderMouseRegion

createRenderObject