How do I associate a filetype with an icon?

Question

I have written preview handlers for a couple custom file types. These file types don't have an application by default that can open them. I want to associate an icon with the file types as a signifier that they are custom.

I have tried setting a registry entry for DefaultIcon in HKCR\.<filetype>, but it doesnt appear to work, even after reboots. I do these registry modifications from C#, and the modifications are successful.

The icon file is simply an ico file residing in %APPDATA% for the moment. I plan to add a few more icons, and put these in a dll file. I just want to get it to work before I take those next steps.

How can I set this icon?

Answer 1

Here is a simple .REG file that registers a icon for the file extension .tj

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\.tj]

[HKEY_CLASSES_ROOT\.tj\DefaultIcon]
@="D:\\scratch\\testy\\icons\\tj.ico"

Tested on Win7

Answer 2

This MSDN article explains how to assign custom icons to file types