anchor.diff:    /// Fragment shader editor
     fl.TextEditor editor;
   
  +  /// Recompile button.
  +  fl.Button button;
  +
     /// Text buffer for the editor
     fl.TextBuffer buffer;
   
  
positive.code:   editor.show();
    return fl.run();
  }
  
negative.code: 
  import 'package:dartgl/dartgl.dart';
  import 'package:fltk/fltk.dart' as fl;
  
  /// More generic 2D GL canvas based on opengl.dart
  class Gl2DCanvas extends fl.GlWindow {
  