This is a low-priority feature request.
Either by default or by option, sort the cards in a players hand. I'd recommend something like Curse, Victory, Treasure, Actions, with each type sorted by cost. But, maybe there's something better.
The reason: just like stacking cards, it would make it much more obvious where your cards are. If I play a card (say, Village) that's on the right side of my hand, and I draw a Village and it goes on the left side of my hand, it takes more thought and mouse movement to click the new Village than if it appeared in the same place. This would add consistency to the UI, which is always a good thing.
This is a good idea. In fact, I do this when playing IRL.
In general I dislike automatic re-ordering of my hand. It leads to misclicks when playing long action chains.
What might be nice is a "tidy hand" button that sorted your cards for you but only when clicked.