popup "Open with..." menu when picturebox is clicked

I have a picture box, containing e.g. c:\pictures\mypic.jpg
I would like users to be able to edit the picture with a program of their
choice. How can I get a context menu "Open With..." to popup, containing
entries from the registry that would appear if the file was right-clicked in
explorer, and "Open With..." was selected?
(I know how to populate a popup, it's how & where to get the appropriate
registry values I need)
Thanks
Giles