Add mouse-over visual feedback to Preference tabs

[minustime]

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).

Test Plan:

1. Open Preferences menu
2. Mouse over menu items on the left
3. Pointer should display similarly to:

Fixes #5112

[bsclifton]

@bradleyrichter pointer is OK here?

[bradleyrichter]

@bsclifton yep!

[bsclifton]

awesome; looks good, thanks! 😄