Fix MacOS long-press accented char bug

[knubie]

Is this adding or improving a feature or fixing a bug?

bug

What's the new behavior?

See #982 for details on the bug.

How does this change work?

The change works by trying to guess when an insertion from the popover is occurring. It does this by comparing the last keyDown value with the value of onBeforeInput (which is triggered after a selection is made). If the values are different, and the last keyDown value was a number between 1-9, and the text for onBeforeInput falls within the unicode range of an accented character, it will insert the character at the specified range. The range is specified as the current selection, with the focus moved back one character, thereby replacing the non-accented character that was inserted when the long press was initiated.

Have you checked that...?

• The new code matches the existing patterns and styles.
• The tests pass with yarn test.
• The linter passes with yarn lint. (Fix errors with yarn prettier.)
• The relevant examples still work. (Run examples with yarn watch.)

Does this fix any issues or need any specific reviewers?

Fixes: #982
Reviewers: @ianstormtaylor

[ianstormtaylor]

Hey @knubie thanks for the writeup here, helps to understand!

Do the native browser events that are being fired not ever expose selection-related information? I would have assumed that there might be a composition* or beforeinput event that had a Range associated with it telling us where the delete should occur?

[knubie]

Thanks for taking a look @ianstormtaylor

I wasn't able to find any useful range info for Chrome or Firefox, but it's possible that I could have overlooked something (or just don't know where to look). Here's a more detailed breakdown of my findings:

Chrome

Fires onBeforeEvent (synthetic, nativeEvent is TextEvent)
Couldn't find any useful range info here.

Firefox

Fires onBeforeEvent (synthetic, nativeEvent is compositionend)
Couldn't find any useful range info here.

Fires onCompositionEnd (synthetic, nativeEvent is compositionend)
Couldn't find any useful range info here

Safari

Fires onBeforeEvent (native)
event.getTargetRanges() //=> {startOffset: 0, endOffset: 1, ...}

[knubie]

Also worth noting that insertion was completely broken on non-MacOS environments before my last commit (b12ae54), but it doesn't look like the CI tests were able to catch that.

[ianstormtaylor]

Fixed by #3093.