Good one, thank you for the post.
Agreed F6 and SHIFT+F6 - both works. But they are not the same.
F6 in SSMS is "move to the next pane" - [if the cursor is in the query pane, it moves ahead to the result pane]
SHIFT+F6 in SSMS is "move to the previous pane"
Try this: type "SELECT 1" in the query window, execute, you will see result pane and also message pane. Now try F6 and SHIFT+F6 to see the direction of the focus.
The first and the hardest SQL statement I have wrote- "select * from customers" - and I was happy and felt smart.