i hate only having 9 different items to quickly choose from, i think it would be awesome for there to be like 12 items to choose from at the bottom of the screen
this would require a client mod unfortunately to do what you want. it IS possible however to store like 8000 inventories and do something to switch between the inventories. Like save inventory and load inventory, so you can get yourself swords and stuff and save as fighter then get a bunch of blocks and save as builder, then get a bunch of tools and save as worker, then switch to whichever you need at a time. That is possible and I believe already done. But we can not do what you want.