New feedback from Outlook.com (React)
When selecting mesages using SHIFT I canonly SHIFT UP. It does not allow me to select/de-select a message by using the SHIFT key. I also notice that when I SHIFT down the Inbox does not follow what has been selected. It kind of makes the Shift key irrelevant if I cant see whats being selected.
Mario Guzman commented
You cannot select/deselect emails with shift + up/down arrow properly.
In my messages list, I select an email, lets say the 2nd in the list. Then I hold shift and press down arrow several times to select other messages, messages 2-10. When I press the up arrow, I expect the last selected message to become un-selected, so the selection would be 2-9; this is how Windows Explorer functions as well as other applications. The way it currently works, the up arrow is treated like I pressed Shirt + Up to begin with, so messages 1 & 2 are selected.
Mark Ingalls commented
Shift + down arrow extends message selection, but shift + up arrow doesn't shrink selection.