void OnGUI()
    {
        const int height = 20;
        int width = (int)position.width - 16;

        mqoFile = EditorGUI.ObjectField(
            new Rect(0, 0, width, height), "MQO File" ,mqoFile, typeof(Object));

        int buttonHeight = height * 3;
        if (mqoFile != null) {
            if (GUI.Button(new Rect(0, buttonHeight, width / 2, height), "Convert")) {
                MQOLoaderScript mqoLoader = new MQOLoaderScript(mqoFile);
                mqoFile = null;		//read out
            }
        } else {
            EditorGUI.LabelField(new Rect(0, buttonHeight, width, height), "Missing", "Select MQO File");
        }
    }
    void OnGUI()
    {
        const int height = 20;
        int       width  = (int)position.width - 16;

        mqoFile = EditorGUI.ObjectField(
            new Rect(0, 0, width, height), "MQO File", mqoFile, typeof(Object));

        int buttonHeight = height * 3;

        if (mqoFile != null)
        {
            if (GUI.Button(new Rect(0, buttonHeight, width / 2, height), "Convert"))
            {
                MQOLoaderScript mqoLoader = new MQOLoaderScript(mqoFile);
                mqoFile = null;                         //read out
            }
        }
        else
        {
            EditorGUI.LabelField(new Rect(0, buttonHeight, width, height), "Missing", "Select MQO File");
        }
    }