I honestly have found that dragging items around the interface is so painful that I avoid UX that requires it. E.g., I use the "donate to shrine" verb rather than drag items to the shine, *because it is painful to do so*. This comes up all the time, but mostly when dealing with inventory: getting the wiggling little thing to get in the right bag is an exercise in frustration.
As a GUI developer, it feels like there are two layers of the toolkit both trying to hand the d&d of the items, so some refreshes the dX of the mouse gets counted twice.