Sibiling Inserter doesn't insert in Firefox and Safari

[bph]

Describe the bug
When clicking the sibling inserter between blocks it doesn't insert a new block but focuses on the block again.
Only in Firefox.

To Reproduce
Steps to reproduce the behavior:

1. Open Firefox Browser
2. Add to Twitter Embeds and a paragraph
3. click on sibiling inserter to add a block

Bonus bug, if you add a paragraph at the end of the page you are not able to add any other blocks to your post. (Already reported issue #7006)

Expected behavior
Insert a new block

Screenshots
http://recordit.co/x2XzEuyoLc

Desktop (please complete the following information):

• OS: os X 10.11.6
• Browser: Firefox Developer Edition: 60.0b15 (64-bit)
• Browser: Firefox Quantum 58.0.2 (64-bit)

[tofumatt]

I can reproduce this in Firefox Developer Edition 62.0b2 (64-bit) on MacOS 10.13.5.

Looking into it now.

[tofumatt]

I'm just poking around right now but disabling https://github.com/WordPress/gutenberg/blob/master/components/tooltip/index.js#L131 fixed it in Firefox.

EDIT: That's not entirely true. Disabling that and forcing the inserters to always be visible:

// editor/components/block-list/insertion-point.js
render() {
	const { isInserterFocused } = this.state;
	const { showInsertionPoint, showInserter } = this.props;

	return (
		<div className="editor-block-list__insertion-point">
			{ true && <div className="editor-block-list__insertion-point-indicator" /> }
			{ true && (
				<div className={ classnames( 'editor-block-list__insertion-point-inserter', { 'is-visible': true } ) }>
					<IconButton
						icon="insert"
						className="editor-block-list__insertion-point-button"
						onClick={ this.onClick }
						label={ __( 'Insert block' ) }
						onFocus={ this.onFocusInserter }
						onBlur={ this.onBlurInserter }
					/>
				</div>
			) }
		</div>
	);
}

Makes it work. 🤔

[tofumatt]

FYI: git bisect shows 7dff9bd is the culprit here (I suspected).

[tofumatt]

Given forcing the inserter to stay open fixes the bug… I wonder if the bit in the commit about "Hide the outline when we click the in between inserter" is why this is happening, but I'll have to look more later.

[gziolo]

The same issue happens in the latest Safari on macOS.