Reproduction

• In the Flutter repo, cd dev/a11y_assessments.
• flutter run
• Enable the additional use-cases using the switch in the top-right corner of the app.
• Open the RangeSlider use-case.
• Let go of the mouse and trackpad (this is important!). Use the TAB key to focus on the range slider, then use the ARROW RIGHT/LEFT to confirm that the range slider is operable.
• While leaving the range slider focused, hover the mouse cursor over the range slider.
• You may see that the focus highlight disappeared.
• Try using the ARROW RIGHT/LEFT keys to operate the range slider again.

Expected behavior

The keyboard input focus should remain where it was, and using ARROW RIGHT/LEFT keys should continue moving the focused thumb.

Actual behavior

Thumbs do not react to the keyboard after hovering. Attempting to take back focusing by clicking on thumbs using mouse doesn't help.