Conventional computerized devices, such as personal computers, laptop computers, and the like utilize graphical user interface in applications such as operating systems and graphical editors (i.e., web page editors, document editors, etc.) that enable users to quickly provide input and create documents and/or projects using “What You See Is What You Get” (WYSIWYG) technology. In general, using a graphical user interface, a user operates an input device such as a mouse or keyboard to manipulate graphical objects on a computer display. The graphical objects are often represented as icons and the user can operate an input device such as a mouse to move a mouse pointer onto an icon (i.e., graphically overlapping the icon) on the graphical user interface. By depressing a mouse button, the application such as the operating system desktop selects the icon and if the user maintains the mouse button in a depressed state, the user can drag the icon across the graphical user interface. By releasing the mouse button, the icon is placed on the graphical user interface at the current position of the mouse pointer.
Using graphical user interface technology, users can create and update documents or graphics comprised of multiple logical layers. A layer can be a collection of document elements such as text and images grouped together for collective editing and manipulation. The collection is separated from other collections and metaphorically constitutes a transparent overlay covering the document substrate (i.e., a virtual model of the physical medium a document will be rendered onto by a document editor). The stack of these overlays has a logical order with higher overlays covering and possibly occluding lower overlays where elements overlap.
Documents and graphic images are often created as a vertical (or horizontal) stack of logical layers. Each layer contains certain elements such as text or images. The layers have an implied order such that elements in the topmost layer cover elements in the next lower layer and so on down to the lowest layer.