A mobile terminal comprising: an interface unit configured to connect to an external display device; a display; and a controller configured to: while the mobile terminal is connected to the external display device via the interface unit, transmit a desktop window screen, via the interface unit to the external display device, and while the mobile terminal is connected to the external display device via the interface unit, and while the external display device is displaying, based on the transmitted desktop window screen, the desktop window screen including a plurality of shortcut icons corresponding to a plurality of certain pre-registered applications executable on the mobile terminal and being capable of executing operations in a desktop window environment, transmit an application desktop window screen of an application corresponding to a shortcut icon selected among the plurality of shortcut icons based on a user input, via the interface unit to the external display device, for display by the external display device, wherein the application corresponding to the shortcut icon selected based on the user input is a gallery application and the transmitted application desktop window screen of the application comprises a plurality of pictures, and wherein, while the mobile terminal is connected to the external display device via the interface unit, a screen layout of the mobile terminal displayed on the display and a layout of the desktop window screen displayed by the external display device are different and the screen of the mobile terminal displayed on the display is maintained in a current state. an interface unit configured to connect to an external display device; a display; and a controller configured to: while the mobile terminal is connected to the external display device via the interface unit, transmit a desktop window screen, via the interface unit to the external display device, and while the mobile terminal is connected to the external display device via the interface unit, and while the external display device is displaying, based on the transmitted desktop window screen, the desktop window screen including a plurality of shortcut icons corresponding to a plurality of certain pre-registered applications executable on the mobile terminal and being capable of executing operations in a desktop window environment, transmit an application desktop window screen of an application corresponding to a shortcut icon selected among the plurality of shortcut icons based on a user input, via the interface unit to the external display device, for display by the external display device, wherein the application corresponding to the shortcut icon selected based on the user input is a gallery application and the transmitted application desktop window screen of the application comprises a plurality of pictures, and wherein, while the mobile terminal is connected to the external display device via the interface unit, a screen layout of the mobile terminal displayed on the display and a layout of the desktop window screen displayed by the external display device are different and the screen of the mobile terminal displayed on the display is maintained in a current state. while the mobile terminal is connected to the external display device via the interface unit, transmit a desktop window screen, via the interface unit to the external display device, and while the mobile terminal is connected to the external display device via the interface unit, and while the external display device is displaying, based on the transmitted desktop window screen, the desktop window screen including a plurality of shortcut icons corresponding to a plurality of certain pre-registered applications executable on the mobile terminal and being capable of executing operations in a desktop window environment, transmit an application desktop window screen of an application corresponding to a shortcut icon selected among the plurality of shortcut icons based on a user input, via the interface unit to the external display device, for display by the external display device, wherein the application corresponding to the shortcut icon selected based on the user input is a gallery application and the transmitted application desktop window screen of the application comprises a plurality of pictures, and wherein, while the mobile terminal is connected to the external display device via the interface unit, a screen layout of the mobile terminal displayed on the display and a layout of the desktop window screen displayed by the external display device are different and the screen of the mobile terminal displayed on the display is maintained in a current state.