void InitOutlineViewAndButton() { // Extract the remaining views from our custom layout. pdfOutlineView = FindViewById <PdfOutlineView> (Resource.Id.outlineView); if (pdfOutlineView == null) { throw new IllegalStateException("Error while loading CustomFragmentActivity. The example layout was missing the outline view."); } var outlineViewListener = new DefaultOutlineViewListener(fragment); pdfOutlineView.SetOnAnnotationTapListener(outlineViewListener); pdfOutlineView.SetOnOutlineElementTapListener(outlineViewListener); pdfOutlineView.SetBookmarkAdapter(new DefaultBookmarkAdapter(fragment)); var openOutlineButton = FindViewById <ImageView> (Resource.Id.openOutlineButton); openOutlineButton.Click += (sender, e) => pdfOutlineView.Show(); openOutlineButton.SetImageDrawable(TintDrawable(openOutlineButton.Drawable, ContextCompat.GetColor(this, Resource.Color.pspdf__color_white))); }