title: Selector with mouse and custom right click
body: <p>Last time, I wanted to make a little application with draggable elements.
  <br>But now, I want to improve my code.
  <br>First, please have a look at my plunker project, where i pasted al my code in.
  <a href="http://next.plnkr.co/edit/gD9Q3NYQES4OMVmY" rel="nofollow noreferrer">http://next.plnkr.co/edit/gD9Q3NYQES4OMVmY</a>
  <br><br>
  <strong>What i want to do: Step 1</strong><br>
  What i want to do now, is that you can select 2 or 3 draggable items. How? I want to make that like on some software systems, on which you can select the items with just crop a box over the items and then all selected items get a background (for showing they are selected).</p>
  
  <p><b>Now Step 2</b>
  <br>If you click NOT on an item, the custom right-click is just like this: <a href="https://prnt.sc/lmh7a6" rel="nofollow noreferrer">https://prnt.sc/lmh7a6</a><br>
  But if you right click on an item, you should be able to execute some other action like deleting it.<br>But if you select a couple of items, you should be able to delete them all or something like this.
  <br><br>
  Thank you guys, for all help :)</p>