title: Rstudio shiny renderDataTable headers multi line?
body: <p>I have a <code>renderDataTable</code> table in Rstudio Shiny that I build with some columns I want to have the header going multi-line, so that a long header string takes a small amount of horizontal space. E.g.:</p>
  
  <p>My long header column is called <code>a_very_long_header</code> in my data.frame, and with the <code>colnames</code> trick below I can turn it into <code>a-very-long-header</code>, which then turns into an ugly multi-line header:</p>
  
  <pre><code>shinyServer(function(input, output, session) {
    output$dt &lt;- renderDataTable({
    data =     data.frame(a_very_long_header=rnorm(10),a=rnorm(10),b=rnorm(10),c=rnorm(10),d=rnorm(10),e=rnorm(10),f=rnorm(10),g=rnorm(10),h=rnorm(10),i=rnorm(10),j=rnorm(10),k=rnorm(10),a1=rnorm(10),b1=rnorm(10),c1=rnorm(10),d1=rnorm(10),e1=rnorm(10),f1=rnorm(10),g1=rnorm(10),h1=rnorm(10),i1=rnorm(10),j1=rnorm(10),k1=rnorm(10))
    colnames(data) = c("a-very-long-header","a","b","c","d","e","f","g","h","u","j","k","a1","b1","c1","d1","e1","f1","g1","h1","u1","j1","k1")
      return(data)
     })
  })
  
  
  shinyUI(navbarPage("Foo", id="page", collapsable=TRUE, inverse=FALSE,
     tabPanel("Bar",
         dataTableOutput("dt")
        )
     )
  )
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/7indt.jpg" alt="enter image description here"></p>
  
  <p>Is there a more elegant way to turn <code>a_very_long_header</code> into <code>a very long header</code> so that it prints the header in multi-line?</p>