I have to make a prototype application where I superimpose a small image over the file icons of a given folder.
Let's say I have a folder /MyDocuments/
and there are three files /MyDocuments/Doc1.rtf /MyDocuments/Doc1.pdf and /MyDocuments/Doc1.jpg
and I have an image **myicon.png**, now I have to superimpose this image myicon.png over the file icons of all the three files present in /MyDocuments/

I understand that I can use the methods in **NSWorkspace sharedWorkspace** to get and set the file icons for these files, but I have no idea how to use the image **myicon.png** and superimpose it over the existing icons of these files.

If anyone has seen the Dropbox application (dropbox.com), then it is similar to the way you see changed icons in your dropbox folder

I assume it would be done using NSImage but I have no idea how to do it.

Note: the image myicon.png will only occupy the top left part of the original icon of these files i.e. the image should not completely overlap with the existing icons but only the 1/4th portion on the top left should be occupied.