}
    /* The tooltip is either not visible, or the mouse is over a different
    ** element, so clear the dwell timer, and record the new element id and
    ** mouse position. */
    stopDwellTimer();
    if(ix >= 0){
      tooltipInfo.ixHover = ix;
      tooltipInfo.posX = e.clientX;
      tooltipInfo.posY = e.clientY;
      stopCloseTimer();
      if(tooltipInfo.dwellTimeout>0){
        tooltipInfo.idTimer = setTimeout(function() {
          tooltipInfo.idTimer = 0;
          stopCloseTimer();
          showGraphTooltip();
        },tooltipInfo.dwellTimeout);

    }
  };
  function nodeHover(e){
    /* Invoked by mousemove events over a graph node */
    e.stopPropagation()
    if(tooltipInfo.ixHover==-2) return
    tooltipInfo.ixHover = -2
    tooltipInfo.posX = e.clientX
    tooltipInfo.posY = e.clientY
    tooltipInfo.nodeHover = this
    stopCloseTimer();
    if(tooltipInfo.dwellTimeout>0){
      tooltipInfo.idTimer = setTimeout(function() {
        tooltipInfo.idTimer = 0;
        stopCloseTimer();
        showGraphTooltip();

    window.location.href = tx.baseUrl+"/info/"+p.h
    e.stopPropagation()
  }
  function findTxIndex(e){
    /* Look at all the graph elements.  If any graph elements that is near
    ** the click-point "e" and has a "data-ix" attribute, then return
    ** the value of that attribute.  Otherwise return -1 */
    var x = e.clientX + window.pageXOffset - absoluteX(canvasDiv);
    var y = e.clientY + window.pageYOffset - absoluteY(canvasDiv);
    var aNode = canvasDiv.childNodes
    var nNode = aNode.length;
    var i;
    for(i=0;i<nNode;i++){
      var n = aNode[i]
      if( !n.hasAttribute("data-ix") ) continue;
      if( x<n.offsetLeft-5 ) continue;

    var dest = tx.baseUrl + "/timeline?r=" + encodeURIComponent(br)
    dest += tx.fileDiff ? "&m&cf=" : "&m&c="
    dest += encodeURIComponent(tx.rowinfo[ix].h)
    return dest
  }
  function clickOnGraph(e){
    tooltipInfo.ixHover = findTxIndex(e);
    tooltipInfo.posX = e.clientX;
    tooltipInfo.posY = e.clientY;
    showGraphTooltip();
  }
  function showGraphTooltip(){
    var html = null
    var ix = -1
    if( tooltipInfo.ixHover==-2 ){
      ix = parseInt(tooltipInfo.nodeHover.id.match(/\d+$/)[0],10)-tx.iTopRow