This would act exactly the same as the current scroll case, except the scrolls in it wouldn't be sold to vendors using the "Sell All" option.
The scroll case is brilliant but it mostly serves only as an in-between looted scrap scrolls and the vendor, scrolls that you actually want to carry on your person either need to be risked in a second case (i've read stories of people who lost them all due to the system selling from that case instead of the other, randomly) or you simply leave them in your inventory as standard.
Adding a "Locked Scroll Case" would allow people to actually have somewhere to store their scroll. I can't imagine this'll be overly hard to achieve seeing as most of the work is done. Just need to copy the current item and strip the auto sell part of the script from it, rename it and give it a new item ID.
Thank you for reading my suggestion
EDIT: Oh, and if it could also store blank scrolls that'd be awesome, thanks