Improve tooltip accessibility

Feature Requests / Improvements
1

Please, make tooltips accessible.

Balloons tooltips are not accessible (WCAG).
Success Criterion 1.4.13 Content on Hover or Focus is fail.
https://www.w3.org/WAI/WCAG22/Understanding/content-on-hover-or-focus.html
What’s the problems are:

  1. Tooltip text automaticaly hide on mouseout. User can not copy text from tooltip.
  2. Tooltip should hide if user click Esc button on keyboard. In this moment this don’t work.

Use aria-label for tooltip text is best approach, because give accessible element name for screen readers.
But Balloons tooltip based on CSS content not realize functionalities from points 1 and 2.