Just had a thought while messing around in my multi-layer backpacks that I use for storing building blocks;
It'd be nice to have something like what JEI/NEI has to go back one recipe - just to go up one nested backpack level, rather than having to close the GUI and reopen it.
Maybe the open backpack key (X) could be used?

Thanks for the suggestion!

Perhaps. This will actually be trickier than you may think, as currently I don't keep track of if a backpack is inside of another, when right clicking a new one to open it directly it simply closes the old one and opens the new one, just like any other backpack. To accomplish going backwards, I would have to implement some sort of data saving mechanism, and while that would definitely be doable, it wouldn't be trivial.

So my question to you is this: Would you use this feature a lot? Is it something worth devoting a fair bit of time on, or is my time better spent working on other stuff?

Thanks!

Good point.
As of now it does seem like something that I would use a lot, but it might not stay that way as it was just for building purposes, and after I finish building things it may get phased out.
Unless something comes up that would make it a load easier, it's really more a quality of life thing rather than an actual need for the mod so I'd say your time would be better spent elsewhere. :)

Maybe let you press the open backpack hotkey while in a backpack inventory (and JEI not selected, ideally) to open the one on your back? You don't need to worry about base ones in the inventory as you can directly right click those.

I personally get a little nervous with infinitely nesting bags and won't be going any further than 1 nest (diamond backpack full of diamonds backpacks), so that would be identical to a back button for me.

I would also greatly appreciate a way to 'exit' out of a nested pack. While full hierarchical traversal would be nice, I agree with VT-14 that just permitting the 'open pack' hotkey inside any pack would reopen the one you're actually wearing would be plenty useful.

In a similar vein, if you can determine that the bag currently open is not the one being worn, then add an additional <- button if the buttons upgrade is applied which switches to the worn bag inventory. (Or just exists in all bags with button+nested applied, but doesn't do anything useful for non-actually-nested bags?)

Add Keybinds To Traverse Open Backpacks