I have two TImages, one on top the other, which are exactly the same size.
The one on top is transparent and is updated from a memory bitmap for
panning and zooming.  The one underneath contains an image which is for
alignment purposes.  The problem I'm having is that the images don't always
update properly.  Sometimes both the images seem to only partially update.
( ImageOnForm is on top of CurtainImage )

I've tried things like this:

  CurtainImage.Update;
  ImageOnForm.Update;

  ImageOnForm.Update;
  CurtainImage.Update;

  CurtainImage.Visible := false;
  ImageOnForm.Update;
  CurtainImage.Visible := true;

  ImageOnForm.Visible := false;
  ImageOnForm.Visible := true;

None of these seem to work every time.  Can I combine these two images in a
memory bitmap and display them together afterwards?  Is this considered
double buffering?

Any suggestions?

Thanks in advance,

Dave