I like how all the ideas Vorspire has brought to the table, were already explained prior to him saying it, yet this guy completely gives credit to him... amazing...
My explanation didn't take 2 posts to get the point across and was easy enough to understand at a mere single sentence...
You could use a special container that would allow players to drop spell scrolls into it to add their spells to the gump, or remove them by taking the scrolls out.. that way you don't need to make a back-end gump for adding/removing.
...which had nothing to do with keeping the container inaccessible like James420 suggested...
You could make it sorta drag and drop. Make the gump container driven. But not open-able as a container. Sorta like what you mentioned, but gump driven too. I suggest looking into the transmodifcation (or w/e it's called) box in the socket system as an idea of how to do it.
...and was never proposed to circumvent that theory, since there are no references to accessibility for the container in their following post...
It's a box that lets people create/mod items by matching the right recipes up in the box. It allows one to add stuff to the container, and then displays it's info in this gump that it opens. You could make a similar container that held the actual spells. Then make a gump that is driven by the container. It would know which spells the player had by checking the container for the spells that are in it.
The box which I speak of is part of the XML Sockets system here in the releases section. It should be a good starting base to get some ideas on where to start with your creation.
...therefor, under logical conclusion, my idea was not what he explained over 2 posts, indeed `similar` in some aspects but the concepts were different altogether, ultimately making the following post moot;
That's pretty much what I explained in my past two posts...
...
Anyway, here's something I was working on a ong time ago for a RunUO 2.0 shard, it should be working, but I don't think I ever got all the bugs out of it.
It's a container that specifically handles player pets/creatures and stores them in a library style system of containers.
Unless you install the Extended Localizer package, this script will create errors.
I'm not trying to provide you with a working solution, but a possible insight into how you can accomplish your goal.
It does feature a really cool gump design, enjoy.
>>> PetChest.rar as attached.