Being able to reorder the build queue is great!  But the current implementation is a bit lacking:

  (a) It's not obvious where the thing I'm moving will end up until I drop it.  Usually I get stuff in the right place by trial and error.

  ( Dropping into the first slot is particularly tricky (especially annoying since that's usually where I want to go).  The hitbox seems to be about three pixels wide -- too far to the left and the drag has no effect; any farther right, and it drops to the right of the first item.

  (c) If the queue is several pages long, it's difficult to drag from one page to another reliably.

  (d) Many of the building icons look similar to each other, so I have to squint or mouse over each one to figure out whether my drop took effect.

I'm sure you can find a better solution, but two possible directions off the top of my head (these don't deal with pagination, of course):

  (1) Show the drag taking effect as I do it (extra points if the dragged item swaps places with the others using nice smooth animations).

  (2) Show a bright vertical line in the spot where the thing I'm dragging will appear (i.e., between the two items in the queue that the dropped item will be dropped in between).