Original post was about "customize Choose a file to show on this folder icon . . . ."
Not "Change Icon", which is the bottom CUSTOMIZE tab choice - Change Icon WILL USE ' .ddl ' (or .exe and other files - choose any exe file and you will probably find at least 1 icon)
This posting is about choosing a file (an image file) to "show on this folder icon" (the common, little manila folder that all windows folders default to) i believe.
to be clear, i am just responding to your text :
"But when I click on the "Change icon" box, I am not given any other choice than dll files..."