Traditional Approach
Though the move from the command-line interface to the full-screen interface (with or without drop-down menus) changed the way of operation to an object-action sequence of work, the Workplace Shell is even more different.
Let's take two examples.
Drag and Drop
The most obvious way to act on an object is by dragging and dropping its icon using mouse button 2, sometimes called "direct manipulation". The user presses mouse button 1 to select objects and mouse button 2 to drag and drop them. The user simply moves the cursor to the object to be manipulated, depresses mouse button 2 to start the drag, holds the mouse button down while moving the cursor to the target, then releases mouse button 2 to drop the object.
Using drag and drop to perform the same actions described above takes just a few simple steps in OS/2 V2.0:
OS/2 does almost all changes to related data for you, such as changing information about a shadow copy. Some information, like a changed path, has to be updated manually.
If an icon is dragged to a printer, the contents of the object are printed. If the object is a file, then the file's contents are printed; if it is a folder, then a list of the folder's contents is produced. In the same way, dropping an icon on the shredder deletes the object, while dropping it on a folder, workplace or diskette moves it into that object.
The concept of direct manipulation implies that certain types of objects may be dropped in certain locations. For example, a printer object cannot be dropped over another printer object, since it is logically impossible to print a printer. It is therefore necessary to provide some form of indication as to whether a "drop" is allowed on a particular object.
This is done visually, by altering the appearance of the icon representing the object being dragged, whenever a drop operation is not permitted. When the icon is moved over an object or location where a drop is permitted, the destination object shows a box around it. However, this does not mean that the target object will actually be able to correctly handle the object to be dropped.
As some of the functions cannot be done with just the two mouse buttons it may be necessary to use the Alt-, the Ctrl- or the Shift-key as a modifier. For example, depressing the Ctrl-key when dragging an object causes a copy instead of a move operation.
This is discussed in more detail in Presentation Manager and Workplace Shell Application Development and Workplace Shell Implementation.