##

    keycodes:

    in grafic-window:
      Ctrl-S      Save model
      Ctrl-Z      delete last created object
      Ctrl-Y      restore last deleted object
      Ctrl-P      redo last user-application

    in editor-window:
      Ctrl-S      Save model
      Shift-cursorKey  select text
      Ctrl-C      copy selected text
      Ctrl-X      delete & copy selected text
      Ctrl-V      paste previous copied text
      Esc         select object-ID/expression left of cursor
      Ctrl-P      redo last user-application

    in browser-window:
      Ctrl-P      redo last user-application