title: Material UI - MultiSelect Popup Anchor Moving on Select
body: <p>I noticed this when upgrading from Material UI 4.2.0 to 4.9.10, but through troubleshooting, I believe this behavior started with version 4.8.3</p>
  
  <p>When using a Select with the multiple attribute, the popup menu moves upon selection of the first item.  I have other examples where it moved several times as multiple items are selected, but in the example I'm providing here, it seems to just happen when choosing the first item.  Here's a codesandbox demonstrating this: <a href="https://codesandbox.io/s/recursing-morse-2omxy?fontsize=14&amp;hidenavigation=1&amp;theme=dark" rel="noreferrer">https://codesandbox.io/s/recursing-morse-2omxy?fontsize=14&amp;hidenavigation=1&amp;theme=dark</a></p>
  
  <p>Here's the same code sample, but using Material UI 4.8.2.  When I choose items from this example, the menu remains anchored to where it was when it popped up: <a href="https://codesandbox.io/s/recursing-frost-pxlds?fontsize=14&amp;hidenavigation=1&amp;theme=dark" rel="noreferrer">https://codesandbox.io/s/recursing-frost-pxlds?fontsize=14&amp;hidenavigation=1&amp;theme=dark</a></p>
  
  <p>My preferred behavior here is the second example, where the menu doesn't jump around on me as I'm selecting.  I've looked through the API, and have tried specifying different anchors, but so far have not been able to keep the popup menu from moving around.  Does anyone know of how to keep the menu in place with version 4.8.3 and beyond?</p>