Implementations for downloadable cartridges for a multi-tenant Platform-as-a-Service system are disclosed. When the user’s context changes, the context-sensitive commands are automatically removed from the user interface. A rotatable tray is provided under the cooling unit, so that an ice-separating member attached to the cooling unit pushes ice upon rotation of the tray, allowing the ice to be discharged in a direction opposite to the rotating direction of the tray. Therefore, a plurality of IDTs can be connected to one RDT.