Allow reuse of existing custom icons in other cards
Since many of us use custom icons, after uploading each custom icon to a card, it should be stored in cache somewhere.
In the dropdown to change and icon, it'd also be beneficial to have a fifth option: to reuse an existing custom icon. Users don't generally store each custom icon, locally, after customizing a card.
Since the card's custom icon is already stored by SafeInCloud, an extra menu option, with previously user-uploaded custom icons, would be quite useful to choose from.