 
     # callbacks
     #
+    unselectedLinkOpacity = 0.1
+    selectedLinkOpacity = 0.8
+
     node_mouseover: ->
       klass = $(this).attr('data-id')
       d3.selectAll(".link").
         filter((d) -> !d.connects(klass)).
         transition().
         duration(200).
-        style("opacity", 0.2)
+        style("opacity", unselectedLinkOpacity)
 
     # this is used as link_mouseout, too
     node_mouseout: ->
       d3.selectAll(".link").
         transition().
         duration(200).
-        style("opacity", 0.6).
+        style("opacity", selectedLinkOpacity).
         selectAll(".link_label").
         transition().
-        style("opacity", 0)
+        style("opacity", 0) # labels
 
     link_mouseover: ->
       current_id = $(this).parent().attr("data-cid")

          if d.cid == current_id
            item.selectAll(".link_label").transition().style("opacity", 1)
          else
            item.transition().duration(200).style("opacity", 0.2)

    # this method is called every time we're updating the chart
    refresh: =>

        attr("transform", "translate(#{@margin.left}, #{@margin.top})")
      @links = @draw_links()
      @nodes = @draw_nodes()
      $("g.node").qtip
        content:
          text: -> $(this).attr('title')
        show:
          event: 'mouseover' # silly IE
        hide:
          event: 'mouseout'  # silly IE


    draw_links: =>
