Question: What I'm trying to achieve is to drag the widget anywhere on the screen.
The solution below allows me to drag but goes beyond the limit of the screen.

Are there any max/min function I can apply here or the corresponding calculation to keep the widget inside the height and width of the screen.

```
  @override
  Widget build(BuildContext context) {
    return Sizer(builder: (context, orientation, deviceType) {
      return MaterialApp(
          debugShowCheckedModeBanner: false,
          home: Container(
              decoration: const BoxDecoration(
                color: Colors.transparent,
                image: DecorationImage(
                  image: AssetImage('assets/images/due.jpeg'),
                  fit: BoxFit.cover,
                ),
              ),
              child: Scaffold(
                  extendBody: true,
                  backgroundColor: Colors.transparent,
                  body: Stack(
                    children: <Widget>[
                      Positioned(
                          left: offset.dx,
                          top: offset.dy,
                          child: GestureDetector(
                            onPanUpdate: (details) {
                              setState(() {
                                offset = (Offset(offset.dx + details.delta.dx,
                                    offset.dy + details.delta.dy));
                              });

                            },

```

Answer: 
right click on D, then click on Edit Alias...

Note: this is how i do in window.
"Labels" will appear as "Active" only when you drag a measure from your Data pane to the "Lable" box inside the Marks pane

This is the best practice to apply any lables, dont use Edit Alias without understanding how Tableau works.