anchor.diff:  RUN ln -s /usr/local/share/phantomjs-1.9.7-linux-x86_64/bin/phantomjs /usr/local/share/phantomjs
   RUN ln -s /usr/local/share/phantomjs-1.9.7-linux-x86_64/bin/phantomjs /usr/local/bin/phantomjs
   RUN ln -s /usr/local/share/phantomjs-1.9.7-linux-x86_64/bin/phantomjs /usr/bin/phantomjs
  +
  +#===========================
  +# Configure Virtual Display
  +#===========================
  +RUN set -e
  +RUN echo "Starting X virtual framebuffer (Xvfb) in background..."
  +RUN Xvfb -ac :99 -screen 0 1280x1024x16 > /dev/null 2>&1 &
  +RUN export DISPLAY=:99
  +RUN exec "$@"
   
   #=====================
   # Set up SeleniumBase
  
positive.code:   && apt-get install -y google-chrome-stable \
    && rm -rf /var/lib/apt/lists/*
  
  #===================
  # Timezone settings
  #===================
  # Full list at http://en.wikipedia.org/wiki/List_of_tz_database_time_zones
  #  e.g. "US/Pacific" for Los Angeles, California, USA
  ENV TZ "America/New_York"
  # Apply TimeZone
  RUN echo $TZ | tee /etc/timezone \
    && dpkg-reconfigure --frontend noninteractive tzdata
  
  #========================================
  # Add normal user with passwordless sudo
  #========================================
  RUN sudo useradd seluser --shell /bin/bash --create-home \
    && sudo usermod -a -G sudo seluser \
    && echo 'ALL ALL = (ALL) NOPASSWD: ALL' >> /etc/sudoers
  
  #===================
  # Install PhantomJS
  
negative.code: # SeleniumBase Docker Image
  FROM ubuntu:14.04
  
  #=======================================
  # Install Python and Basic Python Tools
  #=======================================
  RUN apt-get update && apt-get install -y python python-pip python-setuptools python-dev python-distribute
  
  #=================================
  # Install Bash Command Line Tools
  #=================================
  RUN apt-get -qy --no-install-recommends install \
      sudo \
      unzip \
      wget \
      curl \
      vim \
      xvfb \
    && rm -rf /var/lib/apt/lists/*
  
  #========================================
  # Add normal user with passwordless sudo
  #========================================
  RUN sudo useradd seluser --shell /bin/bash --create-home \
    && sudo usermod -a -G sudo seluser \
    && echo 'ALL ALL = (ALL) NOPASSWD: ALL' >> /etc/sudoers
  
  #==============================
  # Locale and encoding settings
  