Dimensions doesn't work as expected on initially entering split-view (iPad)

Description

It seems that when you initially enter split-view on an iPad, Dimensions does not update as expected. Specifically, the “change” event does not fire and Dimensions.get('window').width does not return the updated width.

After resizing the views, Dimensions goes back to updating as expected.

React Native version:

(Note that the same behavior is observed on the latest version of React Native.)

React Native Environment Info:
    System:
      OS: macOS 10.15.2
      CPU: x64 Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
      Memory: 21.93 MB / 16.00 GB
      Shell: 3.2.57 - /bin/bash
    Binaries:
      Node: 10.20.1 - /usr/local/bin/node
      Yarn: 1.22.4 - /usr/local/bin/yarn
      npm: 6.14.4 - /usr/local/bin/npm
      Watchman: 4.9.0 - /usr/local/bin/watchman
    IDEs:
      Android Studio: 3.6 AI-192.7142.36.36.6308749
      Xcode: /undefined - /usr/bin/xcodebuild
    npmPackages:
      @sentry/react-native: ^1.1.0 => 1.1.0 
      react: 16.8.3 => 16.8.3 
      react-native: 0.59.10 => 0.59.10 
    npmGlobalPackages:
      react-native-cli: 2.0.1

Steps To Reproduce

1. Open the app on an iPad.
2. See that Dimensions.get('window').width returns the expected width.
3. Enter split-view.
4. See that the the dimensions change event isn’t fired and that Dimensions.get('window').width returns the old width.
5. Resize the app. See that the dimensions change event fires as expected and that Dimensions.get('window').width returns the expected width.

Expected Results

1. Open the app on an iPad.
2. See that Dimensions.get('window').width returns the expected width.
3. Enter split-view.
4. See that the the dimensions change event is fired and that Dimensions.get('window').width returns the new width.
5. Resize the app. See that the dimensions change event fires as expected and that Dimensions.get('window').width returns the expected width.

Snack and Screen Recording

https://snack.expo.io/@bryanjclark/rn-bug---dimensions

[hblumberg]

This issue has not yet been fixed.

[stale[bot]]

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