title: Multiple ggplot2 plots with plotly
body: <p>I want to use ggplot2 with grid.arrange to generate multiple plots with plotly.
  Some thing similar to this:</p>
  
  <pre><code>library(ggplot2)
  library(gridExtra)
  library(plotly)
  
  
  g1&lt;-ggplot(mpg, aes(displ, hwy, color=factor(year)))+geom_point()
  
  g2&lt;-ggplot(mpg, aes(cyl, hwy, color=factor(year)))+geom_point()
  
  g&lt;-grid.arrange(g1,g2,ncol=2)
  
  ggplotly(g)
  </code></pre>
  
  <p>However, I am getting "Error in gg2list(p) : No layers in plot"</p>
  
  <p>Any suggestions</p>