Open a modal from a tab bar

Moved over from https://github.com/react-navigation/react-navigation/issues/3003
@spencercarli came up with this solution: https://snack.expo.io/SyJKMkFUM
We might need to change the API a bit to make it cleaner but we can document this approach for now!

• If you're suggesting a change/improvement, tell us how it should work

It would be great to get documentation done for this "open modal from tab bar" layout. I've seen it asked a bunch of times in different places as it's a very common/popular requirement.

While not as helpful as writing documentation myself, here are some of the places this was asked, to show it would be useful to have it in the official docs:

• https://stackoverflow.com/questions/46725173/react-navigation-tabnavigator-show-modal
• https://stackoverflow.com/questions/42731093/how-to-push-a-modal-screen-using-reactnavigation
• https://stackoverflow.com/questions/45520898/react-navigation-and-modal-tab-item
• https://stackoverflow.com/questions/46725173/react-navigation-tabnavigator-show-modal
• https://stackoverflow.com/questions/46106117/tabnavigator-with-a-modal-popup-with-react-navigation-like-instagram
• https://stackoverflow.com/questions/42398911/how-do-i-make-a-tabnavigator-button-push-a-modal-screen-with-react-navigation
• https://github.com/react-community/react-navigation/pull/525
• https://github.com/react-community/react-navigation/issues/314
• https://github.com/react-community/react-navigation/issues/1059
• https://github.com/react-community/react-navigation/issues/1576
• https://github.com/react-community/react-navigation/issues/2259
• https://github.com/react-community/react-navigation/issues/1734
• https://github.com/react-community/react-navigation/issues/770

@TomAtterton seems to have a solution in this issue

https://github.com/react-community/react-navigation/issues/1576

He also left the same comment here:

https://stackoverflow.com/questions/42398911/how-do-i-make-a-tabnavigator-button-push-a-modal-screen-with-react-navigation

Anyway, best practice or not, Tom seems to have the only solution? Maybe he could give a slightly longer form answer and that can be used for docs? @spencercarli

I will try to write something up potentially.

查看連結的 Expo Snack 解決方案，以及相關 issue 和 Stack Overflow 討論，以了解所提議的從分頁列到模態框的版面配置。在專案的官方文件中記錄此方法，包括完整範例和任何 API 注意事項；當使用者可以依照文件中的範例從分頁列開啟模態框時，即表示完成。