title: Leaflet Map - second Polygon makes the first layer unclickable
body: <p>I am working on a map of American Community Survey data. Currently I have a primary layer (seen below as <code>plotMerge$incomePerCapita</code>). It works well, has a fully fleshed out popup, image and all. When I add a second layer, to provide county and regional boundaries, the tract boundaries become un-clickable, seemingly masked by the new layer. </p>
  
  <p>If I swap the layer order, the regional boundaries become invisible.</p>
  
  <pre><code>map1&lt;-leaflet()%&gt;%
    addTiles()%&gt;%
  
  addPolygons(data = plotMerge,
            fillColor = ~pal(plotMerge$incomePerCapita),
            color = "#000000", #this is an outline color
            fillOpacity = 0.8,
            weight = 0.2,
            popup=popup)%&gt;%
  addPolygons(data = countyPoly,
              fillColor = "transparent",
             color = "#000000",
             stroke = TRUE,
             weight = 1,
             smoothFactor = 0.5,
             group = "Counties")%&gt;%
  addLegend(pal = pal,
              values  = plotMerge$incomePerCapita,
              position = "bottomright",
              title = "State-wide Income Percentiles",
              labFormat = labelFormat(digits=1))
  
  saveas(map1, "map1.html")
  map1
  </code></pre>
  
  <p>Is there a way to show just the outline of a boundary in a second layer, yet leave the full functionality of the previous layer intact?</p>
  
  <p>Should I be scripting the addPolygons in a different way to show the boundary without imposing a functionally obscure layer?</p>
  
  <p>UPDATE:</p>
  
  <p>I fixed an error and swapped the <code>addPolygons</code> code to get the layers in the right order.</p>
  
  <pre><code>map1&lt;-leaflet()%&gt;%
    addTiles()%&gt;%
  addPolygons(data = countyPoly,
              fillColor = "transparent",
             color = "#000000",
             stroke = TRUE,
             weight = 1,
             smoothFactor = 0.5,
             group = "Counties")%&gt;%
  addPolygons(data = plotMerge,
            fillColor = ~pal(plotMerge$incomePerCapita),
            color = "#000000", #this is an outline color
            fillOpacity = 0.8,
            weight = 0.2,
            popup=popup)%&gt;%
  addLegend(pal = pal,
              values  = plotMerge$incomePerCapita,
              position = "bottomright",
              title = "State-wide Income Percentiles",
              labFormat = labelFormat(digits=1))
  </code></pre>
  
  <p>Thanks for looking!</p>