Hide autocomplete on Enter key press instead of sending message

[npny]

Fixes element-hq/element-web#4721

In handleReturn, if autocomplete is open (countCompletions > 0), then hide() it and swallow the event.

Because the autocomplete continuously edits the composer's content to match the token under selection, by simply hiding it we're left with whatever token was last selected, which is the behaviour one expects for confirmation through Enter.

Contrast this with onEscape which first resets the selection to 0 so that it goes back to the initial bare text regardless of what you had selected at the time, or with onCompletionClicked which first forces the selection of the clicked item's index, then hides (unnecessary in this case because the confirmed item is already selected).

Signed-off-by: Pierre Boyer <[email protected]>

[bwindels]

Hi, thank you for your PR!

We've recently introduced a new composer for editing messages (currently under a labs flag, in src/components/views/elements/MessageEditor.js). The new editor shares the Autocomplete component with the MessageComposerInput. I'm still changing bits in the auto complete support there, so rather wait until that stabilizes to see how these changes can be merged in.

Will report back here when that's done. Thanks for your patience.

[bwindels]

Sorry for the long wait, this looks good to me!