Inventory GUI element

[Boodals]

With the new script inventories, it would be nice to have an easy way to put them in a GUI. I think it is possible with sprite buttons in a table, but having an existing GUI element for it would be way easier.
It would also need to be able to display the player's inventory, otherwise transferring items would take ages. Maybe it could be generalized to display any inventory?

Bonus points for:

• An event when players add/remove items to/from specifically script-owned inventories via these GUI elements (not sure if this is any more feasible than other "item transferred" events though). Might be possible with just the on_gui_clicked event.
• A way to mark an inventory GUI element as the target for quick item transfer (shift click).