A developer case includes a case main body and a carrier tank. A cover may be secured on the display. The controller module receives, from the first service network, a handover request message for handing over from the first service network to a second service network via the wireless module, and determines whether all configurations in the handover request message are compliable or whether there is a protocol error in the handover request message. Length and orientation of retraction or positioning components is also easily adjustable in several ways.