title: How do I integrate GridView inside TabBar in flutter?
body: <p>What I want to achieve is to create <code>Gridview</code> of product widget when subCategory tab pressed which is inside category tab. I would like it to be in a maximum optimized way. Below is structure that i'm trying to achieve. <a href="https://i.stack.imgur.com/0jJRB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/0jJRB.png" alt="enter image description here" /></a></p>
  <p>sorry for inconvenient design which i have quickly created using paint :)</p>