title: NgbModal closes when i click outside despide defining backdrop to static
body: <p>Im using NgbModal to open a template the following way:</p>
  
  <pre><code>this.modalReference = this.modalService.open(template, MODAL_OPTIONS);
  </code></pre>
  
  <p><code>MODAL_OPTIONS</code> is defined the following way:</p>
  
  <pre><code>export const MODAL_OPTIONS: NgbModalOptions = {backdrop: 'static', keyboard: false};
  </code></pre>
  
  <p>The documentation states that the <code>MODAL_OPTIONS</code>definition above is supposed to prevent the modal to be closed when i click outside of it. Thats also what was recommended in this <a href="https://stackoverflow.com/questions/41438160/stop-closing-the-modal-by-clicking-backdrop-or-outside-the-modal">thread</a>. But it doesnt work for me. The modal still closes when i click outside. Does anyone know what causes that behaviour?</p>