I did notice the item image doesn't follow the highlighted selection area when moving items to and from the red "overflow zone" and the image repeats in its original area a few spaces behind the selection area. But beside from that small visual bug it works perfectly. Thank you so much!
Bro, sorry about that, that bug went unnoticed in my test. Thanks for the quick and accurate report. I updated the V3.9 file with a fix to allow mouse and keyboard control between grids (I had left the item image offset adjustment the same as the previous version, which didn't have the extra inventory management, so it kept appearing in the bottom grid even when the manipulation was in the top grid). It worked fine with drag and drop using the mouse, but it caused the visual bug with keyboard and controller. So I fixed that to allow dynamic navigation between grids. Could you download the file again and test it, please? Let me know if you have any questions.
The visual bug is fixed. In my testing I did have a confusing moment when an item refused to discard but I realized you can only discard items in its original zone (i.e. a sword from the red zone moved to the player inventory won't be discardable until moved back to the red zone, and vice versa). Not a huge deal but I can see it leading the player to a confusing moment like it did for me.
I added a series of parameters so that the system doesn't distinguish between an item in the extra grid and an item in the normal inventory grid, so all options will be available for both types of items. Please download the v3.9 file again; I believe everything is now in order. Thank you for all the feedback; I am truly grateful for your help in improving this tool.