Override default iconhandler for *.bmp type

Question

I have written an Iconhandler for my own file type, following the steps in the "Recipe" sample code. It works fine and displays my files with their correct icons. Now I wanted to override the default "*.bmp" handler that Windows apparently provides, with one of my own (adds a frame to the icon image, for example). So I added the Iconhandler to the bmpfile (the alias for *.bmp files) registry entry, but it is not being used. The default handler overrides it. Is there some way to get MY bitmap file handler to be used, rather than the default. Here is the bmpfile registry entry I added:

bmpfile
DefaultIcon
ShellEx
IconHandler (default value is my icon handler dll, which is registered etc.)