title: Shiny - googlevis: Tooltips for gvisPieChart
body: <p>I am trying to create custom tooltips for a googlevis pie chart. </p>
  
  <p>I have found <a href="http://cran.r-project.org/web/packages/googleVis/vignettes/Using_Roles_via_googleVis.html" rel="nofollow">Using Roles via googleVis</a> but I cannot replicate a similar concept to a pie chart. See below for one of my attempts to achive this:</p>
  
  <pre><code>df &lt;- data.frame(year=c("a","b","g"),pop=1:3, pop.html.tooltip=c("alpha","beta","gamma"))
  
    plot(
      gvisPieChart(df,options=list(tooltip="{isHtml:'true'}"))
    )
  </code></pre>
  
  <p>Moreover, I found out that the first column chart example in <a href="http://cran.r-project.org/web/packages/googleVis/vignettes/Using_Roles_via_googleVis.html" rel="nofollow">Using Roles via googleVis</a> is not working properly. Although the certainty concept is working fine, the tooltips are not displayed as defined in Sales.html.tooltip column of dat dataframe. </p>
  
  <p>Apparently, I am having a problem with tooltips in every other chart apart from gvisScatterChart. </p>