Hope that you are able to download new version of ChartJS that I sent to you through email. Please following below code to make the effect that you want:
<?php
ColumnChart::create(array(
"title"=>"Sale Report",
"dataSource"=>$category_amount,
"columns"=>array(
"category",
"sale"=>array(
"label"=>"Sale",
"type"=>"number",
"prefix"=>"$"
),
"cost"=>array(
"label"=>"Cost",
"type"=>"number",
"prefix"=>"$"
),
"profit"=>array(
"label"=>"Profit",
"type"=>"number",
"prefix"=>"$",
"config"=>array(
"type"=>"line",
"borderWidth"=>3,
)
),
),
"options"=>array(
"tooltips"=>array(
"mode"=>"index",
"intersect"=>true,
)
)
));
?>
Please pay attention to the tooltips
in options