A method of executing an application by using a display device that comprises a touch screen, the method comprising: displaying, on the touch screen, an application execution window (620, 630, 640, 650) in a first region of the touch screen and an application execution window (620, 630, 640, 650) in a second region of the touch screen; receiving, via the touch screen, a first input of dragging a portion of a boundary between the first region and the second region; based on the first input of dragging the boundary, adjusting a size of the first region and a size of the second region; displaying, on the touch screen, a list of a plurality of application execution icons including a first application icon that corresponds to a first application; receiving, via the touch screen, a second input of dragging the first application icon in the list of the plurality of application execution icons; and identifying a location where the second input of dragging the first application icon ends on the touch screen: based on the second input of dragging the first application icon being identified as ending in the first region, displaying, in the first region, the first application execution screen, based on the second input of dragging the first application icon being identified as ending in the second region, displaying, in the second region, the first application execution screen, and based on the second input of dragging the first application icon being identified as ending on a boundary region between the first region and the second region, displaying, on the touch screen, the first application execution screen in a third region formed by combining the first region and the second region. displaying, on the touch screen, an application execution window (620, 630, 640, 650) in a first region of the touch screen and an application execution window (620, 630, 640, 650) in a second region of the touch screen; receiving, via the touch screen, a first input of dragging a portion of a boundary between the first region and the second region; based on the first input of dragging the boundary, adjusting a size of the first region and a size of the second region; displaying, on the touch screen, a list of a plurality of application execution icons including a first application icon that corresponds to a first application; receiving, via the touch screen, a second input of dragging the first application icon in the list of the plurality of application execution icons; and identifying a location where the second input of dragging the first application icon ends on the touch screen: based on the second input of dragging the first application icon being identified as ending in the first region, displaying, in the first region, the first application execution screen, based on the second input of dragging the first application icon being identified as ending in the second region, displaying, in the second region, the first application execution screen, and based on the second input of dragging the first application icon being identified as ending on a boundary region between the first region and the second region, displaying, on the touch screen, the first application execution screen in a third region formed by combining the first region and the second region. based on the second input of dragging the first application icon being identified as ending in the first region, displaying, in the first region, the first application execution screen, based on the second input of dragging the first application icon being identified as ending in the second region, displaying, in the second region, the first application execution screen, and based on the second input of dragging the first application icon being identified as ending on a boundary region between the first region and the second region, displaying, on the touch screen, the first application execution screen in a third region formed by combining the first region and the second region.