Settings button: missing tooltip

[afercia]

The "Settings" button in the top bar used to have a tooltip displayed on hover and focus. This is how it looked like in Gutenberg 2.5:

On current master, no tooltip is displayed at all:

Aside:
the hover style is different too, not sure if that's intentional; if so, it should go in a separate issue though.

[afercia]

Looks like the DotTip added for the NUX prevents the tooltip from working correctly. As soon as I remove it, the tooltip is back. I think this ie because IconButtons are supposed to not use tooltips when they have children, assuming the child is some visible text in the button?

[afercia]

One option could be forcing the tooltip to appear, passing both the label and tooltip props:

label={ __( 'Settings' ) }
tooltip={ __( 'Settings' ) }

However, when the DotTips render, there's also a JS warning:
Warning: validateDOMNesting(...): <button> cannot appear as a descendant of <button>.

to my understanding, although the "tips" use a popover component, the "Settings" tip contains a couple buttons and it's "hooked" within the Settings IconButton so apparently validateDOMNesting evaluates the nesting statically?

Regardless, moving the DotTip outside of the IconButton and wrapping both in a wrapper element could solve both issues.

[designsimply]

Tested and confirmed that hovering over the post settings gear icon does not result in showing a tooltip.

^{Seen at http://alittletestblog.com/wp-admin/post-new.php running WordPress 4.9.6 and Gutenberg 3.1.0 using Firefox 60.0.2 on macOS 10.13.5.}

[afercia]

Just realized also the tooltip of the side inserter "Add block" button doesn't appear on hover any longer, for the same reason. To reproduce:

• create a new post
• hover on the "Write your story" area and then on the "plus" button

Actually, the DotTip passed as child to the Inserter ends up being a child of the IconButton rendered by Inserter. The IconButton component doesn't render a tooltip when it has children (because it assumes the children are visible button content), unless the tooltip is forced with the tooltip prop.

Worth reminding forcing the tooltip prop wouldn't solve the validateDOMNesting warning.

I'd suggest to give this issue higher priority, as the implementation of the NUX tips actually broke the tooltips behavior.