title: Controlling both the major and minor grid lines on the y axis
body: <pre><code>library(ggplot2)
  x &lt;- c(1:100)
  y &lt;- c(1:100)
  ch1 &lt;- qplot(x, y)
  ch2 &lt;- ch1 +
          theme(panel.grid.minor = element_line(colour = "white", size = 0.5)) +
          scale_y_continuous(minor_breaks = seq(0, 100, 5))
  ch2 
  </code></pre>
  
  <p>I am making a chart with ggplot and can control the y axis minor grid lines.
  But what do I have to do to contol the y axis major grid lines as well so they are not set automatically (for example in units of 10s, so lines and y unit labels at 10,20,30 etc)?
  I tried <code>major_breaks = seq(0 , 100, 10)</code> but it did not work.
  Thank you for your help.</p>