flutter all widgets on screen hides when keyboard appears - dart

Question

I am using TabBar and a custom searchview, when I click inside TextField to search and keyboard pops up my all view hides, am attaching screenshots below. Is this flutter issue or I am doing wrong in my code. Please have a look at my code. without popping up keyboard my this is working fine.
return new Scaffold(
body: new Container(
// margin: EdgeInsets.all(10.0),
//color: Colors.white30,
child: new Column(
children: <Widget>[
new Container(
height: 70.0,
color: Theme.of(context).primaryColor,
child: new Padding(
padding: const EdgeInsets.all(8.0),
child: new Card(
child: new Container(
child: new Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Padding(
padding: const EdgeInsets.only(left: 3.0),
child: new Icon(Icons.search),
),
new Container(
width: MediaQuery.of(context).size.width - 100.0,
// Subtract sums of paddings and margins from actual width
child: new TextField(
controller: controller,
decoration: new InputDecoration(
hintText: 'Search', border: InputBorder.none),
// onChanged: onSearchTextChanged,
),
),
new IconButton(icon: new Icon(Icons.cancel), onPressed: () {
controller.clear();
// onSearchTextChanged('');
FocusScope.of(context).requestFocus(new FocusNode());
},),
],
),
)
))),
new Flexible(
child: new ListView.builder(
itemCount: productList == null ? 0 : productList.length,
itemBuilder: (BuildContext context, int index) {
return new Container(
child: new Column(
children: <Widget>[
new Container(
margin: EdgeInsets.all(10.0),
child: new Column(
children: <Widget>[
new Column(
children: <Widget>[
new Padding(padding: const EdgeInsets.only(top: 5.0)),
new Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
new Container(
alignment: FractionalOffset.topLeft ,
width: 250.0,
child: new Column(
mainAxisAlignment: MainAxisAlignment.start,
children: <Widget>[
new Text(productList[index].name,
style: new TextStyle(color: Colors.black,
fontSize: 18.0, fontWeight: FontWeight.bold),
)
],
),
),
new Text("£"+productList[index].price.toString(),
style: new TextStyle(color: Colors.black,
fontSize: 18.0, fontWeight: FontWeight.bold
),),
],
)
],
),
new Row(
mainAxisAlignment: MainAxisAlignment.start,
children: <Widget>[
new Flexible(
child: new Column(
crossAxisAlignment: CrossAxisAlignment.start ,
children: <Widget>[
new Text(
productList[index].description,
overflow: TextOverflow.fade ,),
],
))
],
),
new Row(
mainAxisAlignment: MainAxisAlignment.end,
children: <Widget>[
new ListTileItemAddRemove(productList[index]),
new Padding(padding: EdgeInsets.only(bottom: 10.0))
],
)
],
),
),
new Divider(color: Colors.black,)
],
),
);
}),
),
],
)
),
);
when I click inside TextField all widgets disappears. please see below.

Answer 1

I think flutter widgets are resized when keyboard pops up, I've resolved this issue by setting value false of resizeToAvoidBottomPadding inside Scaffold. Issue has been resolved but still I am looking for the reason behind this issue.
return new Scaffold(
resizeToAvoidBottomPadding : false,
body: new Container(
-
-
-
-
}