Did you know that you can use custom group and document icons in DEVONthink? It works just the Mac way: Copy any image that you want to use as the icon of the item; best suitable are images of a square form with a transparent background. Then select the item in DEVONthink and open the Info panel (Tools > Show Info). Select the item’s icon and paste your graphic. It can’t be any easier, can it? By the way: This works exactly how it also works in the Finder. Custom icons are perfect for making an item stand out, e.g., your Inbox group.