Gutenberg: Multiple block can be in a "isHovered" state

[afercia]

Noticed while investigating on improvements for #8033.

There should be just one block in a "isHovered" state at a time. However, the implementation fails and multiple blocks can be in a "isHovered" state, with the related UI and styles displayed:

To reproduce:

• hover a block
• hover the "More Options" ellipsis button on the right
• wait for the tooltip to appear
• at this point, move the mouse up vertically, to hover the right area of the previous block
• both blocks are now in a "isHovered" state

Same happens with the "block mover" buttons on the left.

Repeating the same steps for all the blocks above, all the blocks become "isHovered".

[designsimply]

Tested and confirmed and found that this only happens when moving the mouse _very_ quickly from one control element _after_ the tooltip is triggered to another control element such as the more options, mover, or the block label that appears on hover. (1m20s)

^{Tested using WordPress 4.9.7 and Gutenberg 3.3.0 both in Safari 11.1.2 and Firefox 61.0.1 on macOS 10.13.6.}

Related: #2122

[afercia]

In my testing it happens also without being very fast when moving the mouse. It seems to always happen when moving the pointer vertically in the area highlighted in the screenshot below:

[designsimply]

For completeness, may I ask what OS and browser versions you are using for testing?

[afercia]

I've tested it on mac, latest Chrome and Firefox.

[jorgefilipecosta]

Hi @afercia thank you for reporting this issue. I tried to replicate this issue after all the design changes that happened and I was not able to do it, it was probably solved as a side effect of the design changes. If I missed something feel free to reopen the issue.

[afercia]

Hi @jorgefilipecosta yep, can't reproduce any onger. Thanks.