[Window openSpec:
'((width 900)
  (height 500)
  (font "profontwindows" 32)
  (text "
\"Register signal\"

model when: #onReplaced do: self >>> #onReplaced:.

\"Trigger signal\"

self triggerSignal: #onReplaced
     with: (TextBufferChange start: start
                            before: removed
                            after: replacement).

[(import \"TextView\") browse]
[(import \"TextBuffer\") browse]
")
  )]