When selecting messages, and the message is read, the label should say "Mark unread"

[GretaD]

Expected behavior

1. When i select a read message the label should say "Mark unread" and when i click the button should be turned into unread
2. Also, when on PI the Other category doest show the checkbox. ( I selected the first message)
   

Actual behavior

1. See gif here: Select multiple envelopes at once using shift #3954 (comment)
2. The checkbox to select is shown

Mail app

Mail app version: 1.5.1

[GretaD]

@StCyr please, as discussed, can you have a look whenever you can? Let me know if you need more testing

[StCyr]

I've fixed the "Label" issue but I can't reproduce the 2nd issue here with latest master: