title: <SELECT multiple> - how to allow only one item selected?
body: <p>I have a <code>&lt;SELECT multiple&gt;</code> field with multiple options and I want to allow it to have only one option selected at the same time but user can hold CTRL key and select more items at once.</p>
  
  <p>Is there any way how to do it? (I don't want to remove 'multiple').</p>