title: Change "fill style" or "line style" in Gnuplot automatically
body: <p>I need to plot a grid.  Each segment of a grid can have different color /style. This style correspond to value that is specified in a file. I thought that <code>boxxyerrorbars</code> style can be relevant. I created a file that has 7 columns:</p>
  
  <pre><code>#x  y   xlow  xhi  ylow yhi  style 
  1   1   0.9   1.1  0.5  1.5   0.2
  2   1   1.9   2.1  0.5  1.5   0.4
  3   1   2.9   3.1  0.5  1.5   0.6
  </code></pre>
  
  <p>I make plot using <code>boxxyerrorbars</code> style and first 6 columns from the data:</p>
  
  <pre><code>plot[0:4][0:2] 'aa1.dat' w boxxy fs solid 0.6 nobo 
  </code></pre>
  
  <p>The plot (just three segments of the grid) looks as... (don't have enough reputations to submit the image).</p>
  
  <p>All segments are drawn with style <code>solid 0.6</code>. By changing this number, one can change <code>fill style</code> density. But I need that each segment has its own style, for example, as specified in the 7th column of the data. Maybe, there are other ways. I just need that segments are drawn with a style /color, specified from a file (not inserted by hand to the script). </p>