Animated popups can get stuck open if mouse enters then leaves very quickly

[mogzol]

Pretty much what the title says. I'm on version 4.0.0-alpha.7. Given an element like this:

<Trigger
  action={["hover"]}
  popup={<span>Hello There</span>}
  popupTransitionName="fade"
  mouseLeaveDelay={0}
  popupAlign={{
    points: ["tc", "bc"],
    offset: [0, 3]
  }}
>
  <p>Test</p>
</Trigger>

And a style like the fade animation from rc-animate's examples. Or even something simple like this:

.rc-trigger-popup {
  display: inline-block;
  opacity: 1;
  transition: opacity 1s;
}

.rc-trigger-popup-hidden {
  display: none;
}

.fade-enter-active {
  opacity: 1 !important;
}

.fade-leave-active {
  opacity: 0;
}

For the most part the trigger/popup works normally. Hovering over the "Test" text creates the popup, which fades in, and then fades out when you stop hovering over the text. The issue comes up when you move your mouse quickly over the text. Sometimes it works normally, other times the popup gets stuck open even after the mouse has left. Increasing the mouseLeaveDelay seems to mitigate the problem, but that's not really a solution.

[mogzol]

So it looks like the problem is if the popup changes from visible: true to visible: false before reaching the "motion" status (in Popup.tsx), it gets stuck. A fix seems to just be to set the status to "stable" if visible has changed to false and status is not yet "motion". I'll put up a PR with the fix.