shouldAlwaysShow property
Enables or disables the crosshair.
By default, the crosshair will be hidden on touch. To avoid this, set this property to true.
Defaults to false.
late CrosshairBehavior _crosshairBehavior;
void initState() {
  _crosshairBehavior = CrosshairBehavior(
    enable: true,
    shouldAlwaysShow: true
  );
  super.initState();
}
Widget build(BuildContext context) {
  return SfCartesianChart(
    crosshairBehavior: _crosshairBehavior
  );
}
Implementation
final bool shouldAlwaysShow;