how to control the slidingUpPanel draggable - flutter

Question

i want a slidingUpPanel similar to YouTube comments section. that not open with the scrolling of the content but open and close only from the drag handle by tap or by swipe up/down).
the drag handle is the top section of the slidingUpPanel :
so the draggable should happen only from this drag handle not from the whole body. (you can try the code below to know what i mean)
it means if i scroll the body(the listView builder) the slidingUpPanel keep its place (either open or closed) until i swip it from the drag handle.
my current code:
PanelController panelController = PanelController();
#override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: Stack(
children: [
SlidingUpPanel(
controller: panelController,
maxHeight: MediaQuery.of(context).size.height * .9,
minHeight: MediaQuery.of(context).size.height * .7,
borderRadius: BorderRadius.vertical(top: Radius.circular(40.0)),
panelBuilder: (controller) => Stack(
alignment: Alignment.topCenter,
children: [
GestureDetector(
onTap: () {
panelController.isPanelOpen
? panelController.close()
: panelController.open();
},
child: Container(
color: Colors.transparent,
height: 36.0,
width: MediaQuery.of(context).size.width,
child: Center(
child: Container(
width: 46.77,
height: 4.0,
decoration: BoxDecoration(color: Colors.grey),
),
),
),
),
Padding(
padding: const EdgeInsets.only(top: 40.0),
child: ListView.builder(
physics: const AlwaysScrollableScrollPhysics(),
controller: controller,
padding: EdgeInsets.zero,
itemCount: 20,
itemBuilder: (context, index) {
return Column(
children: [
Padding(
padding: const EdgeInsets.all(8.0),
child: Container(
height: 70.0,
color: Colors.red,
),
),
],
);
}),
),
],
)),
],
),
));
}