title: The keyboard is flashing when focusing on the TextFormField
body: <p>I have this login screen in which when i tap of the TextFormField the keyboard shows up and hide quickly.</p>
  <pre><code>@override
    Widget build(BuildContext context) {
      return Scaffold(
        body: LayoutBuilder(
          builder: (BuildContext context, BoxConstraints viewportConstraints) {
            return SingleChildScrollView(
              child: ConstrainedBox(
                constraints: BoxConstraints(
                  minHeight: viewportConstraints.maxHeight,
                ),
                child: LoginScreenContent(),
              ),
            );
          },
        ),
      );
    }
  </code></pre>
  <p>it worked for me before in another project, but in this one i couldn't identify the cause of the problem even after trying several solutions.</p>