bl4nk
If you're uploading a file, and want to delete another file from the transfer queue (say one that you're editing and no longer need to edit), you can't hit the delete key on your keyboard or the red X on the transfer queue to get rid of it, but you can right click the file and choose to 'Delete' it. Either all three of the ways should work (this is how I imagine it to), or none of them should.