Opencart sort category by drag and drop

Create an Opencart extension which allows users in the back-end admin to drag and drop categories to sort their order. Currently users sort category orders by entering a Sort Order Number value. Drag and drop function must be instant, e.g. Ajax/Jquery or other.

Developer will need to include written permission for redistribution/resale rights of extension. Extension can be a VQMod or other. Must be compatible with all 1.5.2+ and 1.5.3+ versions.