ComparisonWithPEGI_NativeWay.cs

 public override void OnInspectorGUI() {
   
  var controller = (MyMaterialController )target;

  EditorGUILayout.BeginHorizontal();

  EditorGUI.BeginChangeCheck();

  controller .transparency = EditorGUILayout.FloatField("Object's Transparency:", controller .transparency);

  if (EditorGUI.EndChangeCheck())
    controller .RecalculateShaderParameters();

  GUIContent cont = new GUIContent {
     tooltip = "Will load default value",
     image = refreshIcon
  };

  if (controller .transparency != 0.5 && GUILayout.Button(cont, GUILayout.MaxWidth(25), GUILayout.MaxHeight(25)))
    controller .transparency = 0.5;

  EditorGUILayout.EndHorizontal();
 }