It has always been true, until the recent update, that whenever you delete a message, the next message is automatically selected. This does not happen in the recent update. It is very frustrating, since it used to be easy to delete blocks of messages by just hitting the delete key; now you have to click on each new message in the list before you can delete it.
A relates question: When this type of stuff happens, how can we revert to the previous version?
I also find that the same thing (non-selection) happens when you move a message out of the inbox - then nothing is selected. Also, sometimes when you click on a message that wasn't selected, it lights up and then goes dim, indicating that it is no longer selected. Very strange.....
I also find it extremely frustrating that it seems impossible to just mark up a bunch of messages for an collective action - most often deletion, since let's face it, this is the most common action. At least I delete 3 out of 4 messages without ever wanting to open them.
If there is a way to do this, that I have missed, please tell me! Otherwise I'm afraid I will not use Thunderbird.
What I'm seeing happening is, when I delete a message using the Delete button above the message body, or with the Delete key, the list pane shows the message selected, but nothing appears for the message body until I select a different message, then re-select the message that was after the deleted message. Very frustrating!