title: Resizing panels in a GridLayout
body: <p>I want this:</p>
  
  <p><img src="https://i.stack.imgur.com/QtOyP.png" alt="enter image description here"></p>
  
  <p>My frame is a GridLayout (3,2), and all I can have is this:</p>
  
  <p><img src="https://i.stack.imgur.com/9CoeR.png" alt="enter image description here"></p>
  
  <p>I put the button in a panel, I think it's easier.  But how can I change the size of the grid?</p>