title: Cannot resize VirtualBox display
body: <p>I was using Ubuntu on VirtualBox, but I installed Xubuntu desktop and now display of vm is smaller than my monitor and I cannot resize it. <a href="https://i.stack.imgur.com/NEqDA.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/NEqDA.png" alt="enter image description here"></a></p>
  
  <p>How to extend it?</p>