This method is called by the editor's display whenever the display's size (as reported by get-view-size) changes.
If automatic wrapping is enabled (see auto-wrap ) then set-max-width is called with the maximum width of all of the editor's canvases (according to the administrators; call-as-primary-owner in editor-canvas% is used with each canvas to set the administrator and get the view size). If the editor is displayed but not in a canvas, the unique width is obtained from the editor's administrator (there is only one). If the editor is not displayed, the editor's maximum width is not changed.