title: Vuetify expansion panels - how can I capture onOpen/Show onClose/Collapse?
body: <p>I'm new to using Vue.js and Vuetify, I'm messing around with expansion panels, and in my case, I need to be able to destroy some ajax processing taking place when the user switches to another panel. While using bootstrap-vue I was able to handle this with the "show" event and set the value of a watched property (to the id of the panel selected), which each panel could check to see if matches their panel id, and if it didn't, it could cancel some things. (In my case I have some polling going on and I'd like to kill the polling for the panels not being displayed.)</p>
  
  <p>Similarly, when the panel is opened again I'd like to resume some polling.  </p>
  
  <p>Thanks for some help.</p>