title: How to underline text in a plot title or label? (ggplot2)
body: <p>Please pardon my ignorance if this is a simple question, but I can't seem to figure out how to underline any part of a plot title.  I'm using <code>ggplot2</code>.</p>
  
  <p>The best I could find was 
  <a href="https://stackoverflow.com/questions/23525964/underline-ggplot2-facet-titles%20#%20uses%20annotate()%20with%20geom_segment">annotate("segment") done by hand</a>, and I have created a toy plot to illustrate its method.  </p>
  
  <pre><code>df &lt;- data.frame(x = 1:10, y = 1:10)
  
  rngx &lt;- 0.5 * range(df$x)[2]  # store mid-point of plot based on x-axis value
  rngy &lt;- 0.5 * range(df$y)[2]  # stores mid-point of y-axis for use in ggplot
  
  ggplot(df, aes(x = x, y = y)) + 
    geom_point() +
    ggtitle("Oh how I wish for ..." ) +
    ggplot2::annotate("text", x = rngx, y = max(df$y) + 1, label = "underlining!", color = "red") +
    # create underline:
    ggplot2::annotate("segment", x = rngx-0.8, xend = rngx + 0.8, y= 10.1, yend=10.1)
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/VueDy.png" alt="enter image description here"></p>
  
  <p><a href="https://i.stack.imgur.com/VueDy.png" rel="noreferrer">uses bquote(underline() with base R</a></p>
  
  <p><a href="https://stackoverflow.com/questions/23124264/keeping-underline-length-of-a-label-in-r-consistent-with-label-length%20#%20node%20names%20with%20over%20and%20underline">pertains to lines over and under nodes on a graph</a></p>
  
  <p><a href="https://stackoverflow.com/questions/23988052/underline-text-in-a-barplot-in-r">uses plotmath and offers a workaround, but it didn't help</a></p>