title: GoogleVis HTML Tooltips
body: <p>I try to set a picture as tooltip. </p>
  
  <p>Everything works fine with ScatterChart (I use example code from <a href="http://cran.r-project.org/web/packages/googleVis/vignettes/Using_Roles_via_googleVis.html" rel="nofollow">http://cran.r-project.org/web/packages/googleVis/vignettes/Using_Roles_via_googleVis.html</a>). But when I try to use ColumnChart (or any other types) it doesn't work, I see only standard tooltip. What's the problem?</p>
  
  <p>This code works:</p>
  
  <pre><code>df &lt;- data.frame(year=1:11,pop=1:11, pop.html.tooltip=letters[1:11])
  df$pop.html.tooltip[1]&lt;-'&lt;a href="http://www.geckoanalytics.ru"&gt;&lt;img src="http://www.geckoanalytics.ru/images/giraf.jpg" /&gt;&lt;/a&gt;'
  plot(gvisScatterChart(df,options=list(tooltip="{isHtml:'True'}")))
  </code></pre>
  
  <p>This code doesn't work:</p>
  
  <pre><code> df &lt;- data.frame(year=1:11,pop=1:11, pop.html.tooltip=letters[1:11])
   df$pop.html.tooltip[1]&lt;-'&lt;a href="http://www.geckoanalytics.ru"&gt;&lt;img src="http://www.geckoanalytics.ru/images/giraf.jpg" /&gt;&lt;/a&gt;'
   plot(gvisColumnChart(df,options=list(tooltip="{isHtml:'True'}")))
  </code></pre>