title: Detect When TVertScrollBox bottom reached then do some procedure
body: <p>I  have a <code>TVertScrollBox</code>  and a bunch of flow layouts that got generated on runtime over the scrollbox.. its an  app that load posts 
  I want to load  10 new posts(layouts) whenever the user reach the <code>TVertScrollBox</code> bottom..</p>
  
  <p>I tried using  <code>ViewportPositionChange</code> Event </p>
  
  <pre><code>//-scroll is a TVertScrollBox
   uses Math
  procedure TForm1.scrollViewportPositionChange(Sender: TObject;
    const OldViewportPosition, NewViewportPosition: TPointF;
    const ContentSizeChanged: Boolean);
  
  begin
  if CompareValue(NewViewportPosition.Y,  scroll.Content.Height  ) = EqualsValue then
   begin
   ShowMessage('lets start loading new posts');
   end;
  end;
  </code></pre>
  
  <p>the problem with this attempt is it only works when there is two flow layouts present on the VertScrollBox which  obviously means I am doing it wrong..</p>
  
  <p>How can I achieve that correctly ? </p>