Display the type and number of runes in your rune pouch as an overlay on the item, and also in a tooltip.
The text color in the tooltip and overlay.
Whether to display the item overlay (Inventory), the tooltip (Mouse hover), or both.
When you have 4 different runes in your rune pouch, the overlay changes to use a bar to show how many runes you have. The bar is green when you have more than 1000 runes of a type, and turns red when you go below 1000 runes.
n.b. the green bar displays as full anytime you have more than 10k runes.