Editing Genera (operating system) (section)

== User interface ==
The early versions of Symbolics Genera were built with the original [[graphical user interface]] (GUI) [[windowing system]] of the Lisp machine operating system. Symbolics then developed a radically new windowing system named ''Dynamic Windows'' with a ''presentation-based user interface''.<ref>{{cite web |url=http://dspace.mit.edu/handle/1721.1/6946 |title=Presentation Based User Interface |last=Ciccarelli |first=Eugene C. |publisher=DSpace@MIT |date=August 1, 1984|hdl=1721.1/6946 }}</ref> This window system was introduced with Genera 7 in 1986.<ref>{{cite web |url=http://bitsavers.trailing-edge.com/pdf/symbolics/brochures/Genera_7_1986.pdf |title=Genera 7 Brochure |website=Bitsavers }}</ref> Many of the applications of Genera have then been using Dynamic Windows for their [[user interface]]. Eventually there was a move to port parts of the window system to run on other Common Lisp implementations by other vendors as the [[Common Lisp Interface Manager]] (CLIM). Versions of CLIM have been available (among others) for [[Allegro Common Lisp]], [[LispWorks]], and [[Macintosh Common Lisp]]. An open source version is available ([[McCLIM]]).

''Dynamic Windows'' uses [[Type system|typed objects]] for all output to the screen. All displayed information keeps its connection to the objects displayed (''output recording''). This works for both textual and graphical output. At runtime the applicable operations to these objects are computed based on the class hierarchy and the available operations (''[[Command pattern|commands]]''). Commands are organized in [[Hierarchy|hierarchical]] ''command tables'' with typed parameters. Commands can be entered with the mouse (making extensive use of [[mouse chording]]), keystrokes, and with a command line interface. All applications share one command line interpreter implementation, which adapts to various types of usage. The graphical abilities of the window system are based on the [[PostScript]] graphics model.

The user interface is mostly in [[monochrome]] ([[black-and-white]]) since that was what the hardware console typically provided. But extensive support exists for color, using color frame buffers or [[X Window System]] (X11) servers with color support. The ''activities'' (applications) use the whole screen with several panes, though windows can also be smaller. The layout of these activity windows adapts to different screen sizes. Activities can also switch between different pane layouts.

Genera provides a ''system menu'' to control windows, switch applications, and operate the window system. Many features of the user interface (switching between activities, creating activities, stopping and starting processes, and much more) can also be controlled with keyboard commands.

The ''Dynamic Lisp Listener'' is an example of a command line interface with full graphics abilities and support for mouse-based interaction. It accepts Lisp expressions and commands as input. The output is mouse sensitive. The Lisp listener can display forms to input data for the various built-in commands.

The user interface provides extensive [[online help]] and [[context sensitive help]], completion of choices in various contexts.