Nicolas,

tooltip.showAt() shows the tooltip for specified x value passed as parameter not to nearest x value. In order to show tooltip to nearest x value, you can find the nearest x value and pass it in showAt method to display it. Please take a look at below code snippet for showing tooltip for nearest x value.

```
function getNearestXValues(xVal, dps1) {
return [].concat(dps1).sort(function(a, b) {
var diffA = Math.abs(xVal - a.x);
var diffB = Math.abs(xVal - b.x);
return diffA - diffB; // sort a before b when the distance is smaller
})[0].x;
}
function showTooltip(e) {
for( var i = 0; i < charts.length; i++){
if(charts[i] != e.chart) {
charts[i].toolTip.showAtX(getNearestXValues(e.entries[0].xValue, charts[i].data[0].dataPoints));
}
}
}
```

Also, check out this JSFiddle for complete working code.

—-

Manoj Mohan

Team CanvasJS