When I press Shift+M to move an email message to another folder, I start typing
the name of the folder and a drop down appears showing me a list of possible
folders. If there's only one folder in the list, pressing Enter moves the email
to that folder. But if there are many folders in the list, I have to choose
one. What about an option to always choose the first folder in the list unless
I click on one of the others in the list?
Also, I'm still interested in having an option to have the folder tabs
displayed on the bottom of the Thunderbird window instead of near the top.
Thanks.

> When I press Shift+M to move an email message to another folder, I start typing
the name of the folder and a drop down appears showing me a list of possible
folders. ... What about an option to always choose the first folder in the list
unless I click on one of the others in the list?

Accepted.

> Also, I'm still interested in having an option to have the folder tabs
displayed on the bottom of the Thunderbird window instead of near the top.
Thanks.

noted, but you are not going to uplift another feature by mentioning it in an
unrelated bug, instead go to a dedicated issue [Bug 26400] and add more
comments to remind me.

Implemented in Version 4.15 - released on 21/05/2019

Enter should now always chose the top item. The only restriction is that the
folder name must start with the first letters entered (in-name matching doesn't
work).

Also, check out [Bug 26660] - this allows complete canceling of a quickMove
operation with SHIFT+ESC.

Also, I added support for the [Up] key to jump straight to the bottom of
results - in keeping with the "overflow" behavior of popup menus.