Love the mod but here are a few things that could improve it even mode.
Basic:
* Be able to close the popup window with close hotkey/ESC.
* Be able to move position of the popup window - and remembering last position. It's usually in the way.
* The pickup/drop arrow symbol is cut off on left side.
* Show "Back" instead of "Close" to fit other popup windows in the game.
Balance:
* Don't allow any distance 3 and distance 2 full diagonal on basic inserter.
* Don't allow distance full diagonal 3 on any other inserter.
Advanced:
* Have offset on pickup position too - making it only pickup from chosen side.
* Be able to set multiple pickup positions and drop positions - choosen randomly or in a sequence.
* Be able to set sets of pickups and drops with a number/color for each setup.
* Appropriate extra research for new features.
I made an example here. It should use transparent window like the old one of course. Left side if for pickups, right for drops. Included offset in each tile. Useing 4 colors - I even used colors that colorblind easier can see

Blue - Pickup things from west tile left side of belt and every other time (or tries to) on south tile any side and put them down on southeast tile.
Red - Pickup things from west tile right side and put them on two different locations, if you can do both, do it every other time, else where it can.