Is there any way to make the game do the following:
If the inventory screen of character A is open, I want it to change to the inventory screen of character B, if I click on the portrait of character B.
Nope.
P.P.S.: And while you are at it: Is there a hotkey to cycle through the hotbars?! The arrows to do this are just ridiculously small!
Nope...
UI functionality is counterintuitive and somewhat tedious. Larian is listening though, so wait for a patch.