title: HoverCallback or tooltip equivalent for rCharts Morris bar charts?
body: <p>I'm hoping this is a simple question for someone out there.  </p>
  
  <p>I would like to use rCharts to create a simple bar chart with a custom hover-over. I've found sample code I can use to annotate a point graph, but not a bar chart. </p>
  
  <p>The point graph and bar graphs are built with different reference classes (PolyCharts vs. Morris), but I'm hoping syntax may be similar or someone can give suggestions on how to set the HoverCallback properties through rCharts. Below is a code snippet as an example.</p>
  
  <pre><code>require(rCharts)
  
  sex = c("Male", "Female") 
  ttl = c(4132,4399) 
  pct = c(48.4, 51.6) 
  
  dta = data.frame(sex,ttl,pct)
  
  rp &lt;- rPlot(pct ~ sex, data = dta, type = 'point', 
                    tooltip="function(item){return item.ttl +'\n' + item.pct}"
                    )
  str(rp)
  sp$guides(y = list(title = "", min=0,max = 100))
  rp
  
  # Bar Chart (Reference class = Morris)
  
  mp &lt;- mPlot(x = 'sex', y = c('ttl'), data = dta, type = "Bar",
              names.arg=c("Male","Female")
  )
  </code></pre>
  
  <p>Any suggestions, for coding, or documentation I can review would be greatly appreciated. </p>