showDuration property Null safety
The length of time that the tooltip will be shown after a long press is released (if triggerMode is TooltipTriggerMode.longPress) or a tap is released (if triggerMode is TooltipTriggerMode.tap) or mouse pointer exits the widget.
Defaults to 1.5 seconds for long press and tap released or 0.1 seconds for mouse pointer exits the widget.
final Duration? showDuration;