A method of processing data in a digital device, the method comprising: displaying a first application execution screen on a display of the digital device; receiving a first signal for requesting a menu; in response to reception of the first signal, overlaying a menu launcher including a plurality of menu items on the first application execution screen, wherein the plurality of menu items are separately divided into a first part comprising history data of the menu launcher, and a second part of applications executable in the digital device; receiving a second signal for selecting a menu item among the plurality of menu items from the second part, in response to selection of the menu item, magnifying a size of the selected menu item and displaying a plurality of icons for a multi-view mode above the magnified menu item together with the menu launcher overlaid on the first application execution screen, wherein the plurality of icons respectively correspond to one of a first multi-view mode in which a screen is divided into two areas to provide a main window and a single sub-window, a second multi-view mode in which a first single sub-window is provided in the main window in the form of a picture-in-picture, PIP, and a third multi-view mode in which a plurality of sub-windows are provided in the main window in the form of the PIP, receiving a third signal for selecting one of the displayed icons for a multi-view mode corresponding to the selected icon; and in response to reception of the third signal, displaying a second application execution screen corresponding to the selected menu item together with the first application execution screen in the multi-view mode corresponding to the selected icon. displaying a first application execution screen on a display of the digital device; receiving a first signal for requesting a menu; in response to reception of the first signal, overlaying a menu launcher including a plurality of menu items on the first application execution screen, wherein the plurality of menu items are separately divided into a first part comprising history data of the menu launcher, and a second part of applications executable in the digital device; receiving a second signal for selecting a menu item among the plurality of menu items from the second part, in response to selection of the menu item, magnifying a size of the selected menu item and displaying a plurality of icons for a multi-view mode above the magnified menu item together with the menu launcher overlaid on the first application execution screen, wherein the plurality of icons respectively correspond to one of a first multi-view mode in which a screen is divided into two areas to provide a main window and a single sub-window, a second multi-view mode in which a first single sub-window is provided in the main window in the form of a picture-in-picture, PIP, and a third multi-view mode in which a plurality of sub-windows are provided in the main window in the form of the PIP, receiving a third signal for selecting one of the displayed icons for a multi-view mode corresponding to the selected icon; and in response to reception of the third signal, displaying a second application execution screen corresponding to the selected menu item together with the first application execution screen in the multi-view mode corresponding to the selected icon.