I built this feature last weekend, but held off on releasing it due to the visual glitch when dragging and dropping.
But enough people have requested (or outright demanded :P) it that I figured it's better to release it with the minor glitch in place than to not release it at all.
The glitch is that, if the window has been resized, the card you're dragging will appear a little off-position. This doesn't affect anything except that it looks a little weird.
After the next expansion is out, I'll be spending some more time looking for ways to improve it and get rid of that tiny glitch.