title: NSView Subviews interrupting drag operation
body: <p>I have an NSView which is registered for a drag operation.</p>
  
  <p>In that view I have a subclassed NSScrollView, which in itself has an NSImageView in it.</p>
  
  <p>When dragging onto the original NSView, everything is fine, other than when I drag over the aforementioned NSImageView, which seems to interupt the drag and I cannot drop onto it (or in fact, the view underneath it. </p>
  
  <p>The NSScrollView appears to ignore the drag and allows that to go through to the underlying NSView, but how can I do that for the NSImageView so that the Drag/Drop registers through itself, it's superview (the NSScrollView) and onto the underlying NSView.</p>