I have a question (you might probarly know al ready you have things like "ale(3)" it means that there are for of that kind of bottles, but now my question: can you take also only one?? I don't know how you can do that...
Drag a stack out of (or into) your inventory (or container) and hold down the control key before dropping. This will bring up the split stack window, where you can specify how many to move.
At least in the disk version of the game, this can be used to duplicate any stackable items (gold, potions...)
In the split stack window, type in a negative number and hit enter (the checkmark will be greyed out). This can also be done in the trade window.