title: plot legends without border and with white background
body: <p>I have a legend in a plot with a line (from an abline-statement) going through it. How can I achieve that the abline gets invisible in proximity of the legend? This should be achievable by setting the legend background white, without borders, but how can I achieve this?
  Assume the graph should look like this:</p>
  
  <pre><code>windows.options(width=30, height=12)
  plot(1:10)
  abline(v=seq(1,10,1), col='grey', lty='dotted')
  legend(4.8, 3, "This legend text should not be disturbed by the dotted grey lines")
  </code></pre>
  
  <p>And to get it a bit more complicated:
  If the legend interferes with the dots of the dot-plot: How can I achieve that the ablines gets invisible in proximity of the legend (as above), but that the dots are still visible?</p>
  
  <pre><code>windows.options(width=30, height=12)
  plot(1:10)
  abline(v=seq(1,10,1), col='grey', lty='dotted')
  legend(1, 5, "This legend text should not be disturbed by the dotted grey lines, but the plotted dots should still be visible")
  </code></pre>
  
  <p>And finally: Is there a way to introduce line-breaks in legend statements?</p>