User Agent: Mozilla/5.0 (Windows NT 6.3; Win64; x64; rv:71.0) Gecko/20100101 Firefox/71.0

Steps to reproduce:

Under Tools -> Account Settings select a server.
Click on Junk Settings.
In the Do not automatically mark mail as junk if the sender is list click on a mailing list.
Note the space-bar toggles the check-mark.
Use the cursor keys to move the selection bar and note the highlight moves.
Press the space-bar and note the PREVIOUSLY-SELECTED item is toggled (not the current selection.)

Actual results:

Changing the selection by clicking moves the highlight and the space-bar toggles the highlighted item.
Navigating with the cursor keys changed the highlight but the space-bar toggles the previous selection.

Expected results:

Changing the selection with the cursor keys or clicking the mouse should be equivalent.

Marco, can you reproduce this on windows?

@Wayne,

Yes, I can confirm the bug.

I moved to the line above using the cursor key and when I pressed SPACE it toggled the line below check box.

With TAB it moves the focus (see the dotted focus ring) but not the selection background and then it works. Maybe aceman or Geoff can help here.

Thoughts?

The checkboxes are stealing focus from the richlistbox, but it's still changing the selection because the keyboard events are coming from inside it. So I'm preventing the checkboxes from having focus, and simulating the keyboard space/enter action.

Pushed by geoff@darktrojan.net:
https://hg.mozilla.org/comm-central/rev/3a7bdd6a51af
Fix keyboard navigation errors in junk settings address book list. r=khushil

Thunderbird 79.0b2:
https://hg.mozilla.org/releases/comm-beta/rev/516f2af4d727

Thunderbird 78.1.0:
https://hg.mozilla.org/releases/comm-esr78/rev/78411b3c7e26