Mathematica

DynamicModule[{data = "some\ndata"}, EventHandler[
  Framed[Pane[
    InputField[Dynamic[data], String, ContinuousAction -> True,
     Appearance -> None, FieldSize -> {30, {1, Infinity}}],
    ImageSize -> {400, 100}, ImageMargins -> 0,
    AppearanceElements -> {}, FrameMargins -> {{0, 0}, {0, 0}},
    Scrollbars -> {True, True}], Background -> White,
   FrameMargins -> 0, FrameStyle -> Gray]
  , {
   "ReturnKeyDown" :>
    FrontEndExecute[{NotebookWrite[InputNotebook[], "\n", After]}]
   }]]