As we are on the subject of throwing - how to throw a potion during combat? I've read about it but so far I haven't figured out how to do it ...
If you select the "throw" action on the toolbar or by pressing X, then your toolbar should change to show everything in your inventory that's throwable, which you can then filter using the tiny icons in the middle bottom to just show potions/grenades (I think this choice will be preserved until changed) so you can just pick the potion you want and then select the location.
Alternatively you can open up your inventory and right click on the potion and select "throw item" from the pop-up menu. Personally, I think you should also be able to right click on an item in your toolbar and get the same pop-up menu, but unfortunately this doesn't work and left-clicking the item just performs the default action which is throw for things like grenades or bombs, apply to weapons for poisons, but is drink for potions.
