Question

I have an application that gets installed with a Wise installer (EDIT: Wise creates a Setup.exe file, not an MSI). Upon installation, an icon is set for a certain file type:

HKEY_CLASSES_ROOT\.auz\DefaultIcon = C:\Path\To\App\some_icon.ico,0 

Right after the installation, however, Explorer chooses to display this icon using the generic ‘white sheet + application icon’ icon, which is different (and not provided by me).

Upon first launch, the application itself registers icons and other file associations, so that the last run version ‘owns’ those documents. At that point, Explorer changes the icon for this file type and displays the correct one, but when I look at the registry, the value for DefaultIcon is exactly the same.

This is what I’ve tried so far

• Removing all entries from the registry, and writing them myself.
• After the installation, ‘touching’ the value of DefaultIcon, and then launching a small little program that only calls SHChangeNotify(SHCNE_ASSOCCHANGED) (my program does this after updating the file associations in the registry).
• After the installation, killing and restarting Explorer.
• After the installation, using TweakUI to ‘repair’ the icons on the desktop.

None of these work. The only way to get the correct icon is to let the program itself install it. I can’t find any change in the registry. I’m pulling my hair off.

What I would like to avoid

• Testing with another installer software
• Changing the installation script too much (I don’t have Wise itself, as the installer gets built on another machine on demand).
• Embed the icons in the executable.

Any suggestions on how to get Explorer to display the correct icon after installation?

Answer 1

Here’s the solution.

Each file type (let’s say ‘.auz’ in this case) was registered with:

• A DefaultIcon key with the path to the icon resource, and
• A value for the HKEY_CLASSES_ROOT\.auz\(default) value giving a description of the file type, e.g. ‘Foobar Document’.

In addition to this, there was an entry for the ‘Foobar Document’ document type, or more specifically, a key for how to open such documents from the shell:

HKEY_CLASSES_ROOT\Foobar Document\Shell\command\open\(default) = C:\Path\To\App.exe '%1' 

Apparently, this key supersedes the value written for the specific file extension. Because the icons are external to the .exe file, Windows Explorer then used the first icon of the application to create an icon for all files of type ‘Foobar Document’ (that ‘white sheet + application icon’ icon I mentioned).

Now, what I had wrong was that the application itself does change the value of

HKEY_CLASSES_ROOT\.auz\(default) 

to a slightly different value when starting, say ‘Foobar 1.2 Document’ (the problem with not being DRY). Thus, the link to ‘Foobar Document’ was lost, and the .auz files got their icons after the first launch.

So I fixed this all by simply removing the HKEY_CLASSES_ROOT\Foobar Document key altogether, and voilà!