Scales the viewport of one or more graphical windows by a factor. A factor
greater than 1 scales up, a scale factor less than one scales down.
If the command is started from the graphical window's menu, the context menu
or by a mouse stroke then the destination window is implicitly assumed.
In all other cases the destination window must be explicitly defined if the
window layout contains more than one window.
The destination window is identified by a digitized point or by typing its
identifier. Since the identfiers are powers of two (e.g. 1, 2, 4, ...) a
whole destination window set can be defined by adding the identifiers of all
windows of the set (e.g. 1 + 2 + 4 for window 1, 2 and 4). A destination set
containing all windows is described by the identifier -1.