title: Scrollbar doesn't appear in parent control if the child is docked to the edge
body: <p>I wonder why the child control cannot be scrolled even though it cannot fit its container.
  Here is my simple example of the layout:</p>
  
  <p><img src="https://i.stack.imgur.com/X5zSB.png" alt="enter image description here"></p>
  
  <p>I have orange panel and green panel inside. Orange panel has AutoScroll set to true.
  Green panel is docked to top and has minimum width = 150.
  Why the horizontal scrollbar doesn't appear on orange panel?</p>
  
  <p>Without DockStyle=Top everything works fine. I could use Anchors, but I feel more comfortable with docking when creating more complex layouts with many groupboxes and panels stacked on each other.
  I also don't like using AutoScrollMinSize because it sets the limit regardless of what controls are currently visible on the form.</p>
  
  <p>The question is why does it work this way?</p>
  
  <p>P.S. Just let me know if this is by design and there is no other way except Anchors on green panel or AutoScrollMinSize on orange panel. It seems weird to me that it cannot display the scrollbar in that case even though you have child control that cannot fit into its parent and parent has AutoScroll=true. I guess the layout engine doesn't even bother calculating the actual width of the docked control because in theory it is stretched to whatever parent width you have.</p>