A handheld electronic device includes a QWERTY keyboard and is enabled with disambiguation software. A change in the setpoint value for the control of the actuator to the first setpoint value is limited to a first setpoint value change limitation. A third cooling system is configured to provide a second cooling source to the coolant when the first cooling source is unavailable, so that a pressure of the coolant does not exceed a predetermined level when the first cooling source is unavailable. Cross-sections of the joints are point-symmetric or line-symmetric, wherein the end flange and the joint are disposed so that a center of point-symmetry of a pair of interfitted joints is located on or near a centerline of the end flange in the thickness direction.