             svg.selectAll("g#ylines").remove()
             ylabels.attr("opacity", 0)
                    .attr("id", (d,i) -> "ylab#{i}")
+
+        # tool tips
+        celltipfunc = (d) ->
+                             z = d3.format(".2f")(Math.abs(d.lod))
+                             lodlabel = if data.ycat? then data.ycat[d.lodindex] else d3panels.formatAxis(data.y)(data.y[d.lodindex])
+                             return "#{lodlabel}, #{d.poslabel} &rarr; #{z}" if horizontal
+                             "#{d.poslabel}, #{lodlabel} &rarr; #{z}"
+        direction = if horizontal then "north" else "east"
+        celltip = d3panels.tooltip_create(d3.select("body"), cellg.selectAll("rect"), {direction:direction, tipclass:tipclass}, celltipfunc)
 
         myframe.box().raise()
 

                        cells.push({lod: lod, chr:chr, pos:pos, poslabel: data.poslabelByChr[chr][i], posindex:+i, lodindex:+j})
        d3panels.calc_chrcell_rect(cells, xmid_scaled, ymid_scaled)

        # tool tips
        celltip = d3.tip()
                   .attr('class', "d3-tip #{tipclass}")
                   .html((d) ->
                             z = d3.format(".2f")(Math.abs(d.lod))
                             lodlabel = if data.ycat? then data.ycat[d.lodindex] else d3panels.formatAxis(data.y)(data.y[d.lodindex])
                             return "#{lodlabel}, #{d.poslabel} &rarr; #{z}" if horizontal
                             "#{d.poslabel}, #{lodlabel} &rarr; #{z}")
                   .direction(() ->
                       return 'n' if horizontal
                       'e')
                   .offset(() ->
                       return [-10, 0] if horizontal
                       [0,10])
        svg.call(celltip)

        cellg = svg.append("g").attr("id", "cells")
        cellSelect =
            cellg.selectAll("empty")

    # function to remove chart
    chart.remove = () ->
                      svg.remove()
                      d3panels.tooltip_destroy(celltip)
                      return null

    # return the chart function
