This could cause issues with any controls that perform different functions when dragged or clicked.

There are a number of controls that do respond on a simple mousedown event (such as menus), so it's would be just a matter of redefining which controls are necessary to wait for a mouseup, which would then necessitate users remembering which is which.

That's solved fairly trivially by requiring the card to be removed from the machine before the requested cash is dispensed.
Thats how many ATMs in Australia do it.

I'm fine with that as long as we can call real kittens 'land-fish' (a la Stephen Colbert)

Sean Williams.

(Then of course, there's Peter Hamilton, Vernor Vinge, Stephen Baxter, Iain M. Banks...)