If you have another active window than your inventory, you should be able to interact with your inventory stack using a quick-key that shifts it into the window open:

E.g. Cabinet, Trade Window, Vendor (Selling), Monster Loot, GoGuardian or Belt.

Drag and Drop is slow and it's possible to accidentally drop stuff on the floor.
Such an accident is made indefinitely worse by the fact that rare parts now stack.

So:

If stack is in trade/gogu/vendor/monster loot/belt/cabinet and I shift click it: move entire stack to inventory.
and in reverse, if it's in my inventory and I shift click it, it should move into respective monster loot/cabinet/trade/gogu/vendor window.


Another enhancement:
If someone trades you whilst you have an alternate window open, the trade should not succeed.
People trading others whilst they're looting monsters/their belts is an exploit, and should be fixed as one.

Another shortcut should be available to quick drop loot in monsters to the floor, this would make farming a much more efficient task. *especially if you're under fire*