#### 7.2.136 ui-panel

`(ui-panel PANELNAME {on|off} [WINDOW])`
  Do or don't display the given user-interface panel. Case is ignored in panel names. Current PANELNAMEs are:
  geomview
    main panel
  tools
    movimento controls
  appearance
    appearance controls
  cameras
    câmera controls
  lighting
    lighting controls
  obscure
    obscure controls (doesn't seem to exist any more)
  materials
    material properties controls
  command
    command entry box
  credits
    geomview credits
  By default, the `geomview` and `tools` panels appear when geomview starts. If the optional Window is supplied, a `position` clause (e.g. (ui-panel obscure on { position xmin xmax ymin ymax }) sets the panel's default position. (Only xmin and ymin values are actually used.) A present but empty Window, e.g. `(ui-panel obscure on {`)} causes interactive positioning.