This is just a small simple little upgrade that I feel could be implemented into the game with no hassle what so ever and make a rather nice improvement on everybody's display case.
My suggestion is making it so you can either add each item into the display case and have them stay in the order in which you added them. Or you could be able to switch the items around after they are already in the case.
The reason I think you should be able to do this with the display case is because of
1. Say you use your display case the same as me. You store all of the items that you buy and sell on a regular basis inside it and frequently check it so you can quickly look and see what items are getting low in quantity or what items you have plenty of and could sell a few. It would make looking for (a Can of Munster for instance) to see how many you have much easier if you could have all your cans one after another in the display case.
2. If someone asks me if I want to buy anything or if they ask me if I have anything I could sell them its just nice and easy to say take a look at my display case instead of typing out what items or types of items I need or sell. Plus when I have my customers that I do travel runs for or the ones that buy in bulk, it's much easier for them to just go and look at my display and see if i have the quantity of items they want or need. And also when the people who travel for me and sell me plush or flowers or what not are curious as to where they should travel and what items to bring back they can just look at my display and see what items I'm currently lowest in quantity and just go ahead and travel there. I dont even need to be logged on for them to know what item I want them to pick up for me.
Thank you if you took the time to read this. Thank you even more if you liked this idea and think it should be added.