title: how to get custom bottom sheet like one in image? curved bottom sheet in flutter
body: <p>I tried to make some custom bottomsheet in my flutter app. i tried to add grey background in my sheet with roundedrectangleborder in <code>container</code>. but why it doesn't work?
  Here's my code and output:</p>
  <pre><code> void _modalBottomSheetMenu4(){
      showModalBottomSheet(
          context: context,
          builder: (builder){
            return new Container(
              height: 350.0,
              color: Colors.grey[350],
              child: new Container(
                  decoration: new BoxDecoration(
                      color: Colors.white,
                      borderRadius: new BorderRadius.only(
                          topLeft: const Radius.circular(3.0),
                          topRight: const Radius.circular(3.0))),
                          //content starts
                  child: new Container(
                    margin: EdgeInsets.only(right: 5.0,left: 5.0,top: 10.0),                 
              child: new Column(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: &lt;Widget&gt;[
  
  // rounded rectangle grey handle
                  new Container(
                    width: 40.0,
                    height: 5.0,                 
          decoration:
                  new BoxDecoration(
                    borderRadius: new BorderRadius.circular(10.0),
                    color: Colors.grey,
                  ),
  ),
  
                 
  new Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: &lt;Widget&gt;[
          
                   new SvgPicture.asset(&quot;assets/lang.svg&quot;, width: 80.0, height: 80.0, ),
                    
            new Text(&quot;\nSelect Language\n&quot;,
            style: TextStyle(color: Colors.black,fontWeight: FontWeight.bold, fontSize:20.0 )),
  
             new Container(
               padding: EdgeInsets.all(5.0),
              child: new CupertinoButton(   //special button for ios on click fadecolor
                onPressed: () async{
                          Navigator.pop(context);
                         Navigator.of(context).push(new MaterialPageRoute(builder: (BuildContext context) =&gt; new GreetingPage())); 
                                },
                                child: new Text(&quot; Tamil &quot;),
                                color: CupertinoColors.activeBlue,
                                pressedOpacity: 0.4 ,          //opactiy default 0.1
                                minSize: 44.0,                //its has min length 
                  
                              ),
                            ),
  
  
                             new Container(
                               padding: EdgeInsets.all(5.0),
              child: new CupertinoButton(   //special button for ios on click fadecolor
                onPressed: () async{
                        Navigator.pop(context);
                       Navigator.of(context).push(new MaterialPageRoute(builder: (BuildContext context) =&gt; new GreetingPageEng())); 
                                },
                                child: new Text(&quot;English&quot;),
                                color: CupertinoColors.destructiveRed,
                                pressedOpacity: 0.4 ,          //opactiy default 0.1
                                minSize: 44.0,                //its has min length 
                  
                              ),
                            ),
  
  
                                ],
                              ),
                               SizedBox(height: 30.0),
                ],
              ),
                                  ),
                              ),
                            );
                          }
                      );
                    }
      
  </code></pre>
  <p>my output:</p>
  <p><a href="https://i.stack.imgur.com/brk02.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/brk02.jpg" alt="my output sheet" /></a></p>
  <p>expected output:</p>
  <p><a href="https://i.stack.imgur.com/xDWNy.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/xDWNy.jpg" alt="expected output sheet" /></a></p>
  <p>Curved Edges is not visible in my bottom sheet.</p>
  <p>What's mistake I did in code?<br />
  How can I acheive this?</p>
  <p>Thanks in advance.</p>