title: GNUPLOT: pngcairo terminal crop does not completely crop
body: <p>i am printing some png pictures with png cairo terminal:</p>
  
  <pre><code>set terminal pngcairo enhanced transparent size 1440,900 crop font "Palatino,27"
  </code></pre>
  
  <p>as a splot:</p>
  
  <pre><code>set tmargin at screen 1; set bmargin at screen 0; set lmargin at screen 0;
  set view map; set size ratio -1; unset border;
  set output 'pic.png'
  splot 'datafile.bin' binary with pm3d
  </code></pre>
  
  <p>so i want a picture with absolutely no border. I both use the crop options and set margins to 0. Nevertheless, a small white border always remains all around the picture. </p>
  
  <p>Any idea to get rid of it?</p>
  
  <p>Many thanks</p>