title: How to have multiple selection of items on combobox
body: <p>Hey I wanted to know how can I select multiple items from the combobox in XAML? 
  Note: I'm using Data Binding.</p>
  
  <p>Like this image:</p>
  
  <p><img src="https://i.stack.imgur.com/KM5S4.jpg" alt="Image"></p>