The vacuum hopper is uniformly black. This makes it challenging to determine which side is left, right, etc when you are in the tab to set output sides (if you rotate it from its default orientation).

I don't really consider this a bug. When you open the GUI, the block is rotated to the same direction that you're currently looking at the block. I feel it'd be pretty difficult to lose track of orientation within a single drag of the mouse..

Not-A-Bug.
Please comment if you feel this was closed in error.