1. A machine implemented method, comprising: displaying a first set of windows controlled by a first set of user level applications and a second set of windows controlled by a second set of user level applications, and a first user interface of a system level application on a screen space of a display device, wherein the first set of windows and the second set of windows are displayed in a multi-application mode that includes concurrently displaying application windows of a plurality of executing applications; switching from the multi-application mode to a selected applications mode; removing, in response to the switching, the second set of windows from the screen space of the display device while leaving the first set of windows and the first user interface of the system level application displayed; receiving a request to display the second set of user level applications; displaying, in response to the request, the second set of windows on the screen space of the display device while removing the first set of windows, and displaying a second user interface to show user level applications, whose windows have been removed from the screen space and that are executing.