NDSShellExtension

Shell Extension to show Nintendo DS rom icon in Explorer.

It reads the icon stored in the banner of each .nds file (32x32, 4bpp, 16-color palette) and shows it as the file icon in Windows Explorer.

Requirements

• Windows 10/11 64-bit. The DLL must be x64: the 64-bit Explorer does not load 32-bit shell extensions.
• To build: Visual Studio 2022 (or Build Tools) with the Desktop development with C++ workload and the C++ ATL component.

Build

Open NDSFileIcons.sln and build Release | x64, or from a command line:

msbuild NDSFileIcons.sln /p:Configuration=Release /p:Platform=x64

Output: x64\Release\NDSFileIcons.dll. A Win32 build is also available (only useful on 32-bit Windows 10).

Install

Copy the DLL to a permanent folder and register it:

regsvr32 C:\Tools\NDSFileIcons.dll

• From an elevated prompt it registers for all users (HKLM).
• Without admin rights it registers for the current user only (HKCU\Software\Classes), no error.
• regsvr32 /n /i:user C:\Tools\NDSFileIcons.dll forces per-user registration.

Restart Explorer to pick it up:

taskkill /f /im explorer.exe & start explorer

If the generic icon still shows, clear the icon cache with ie4uinit.exe -show.

Uninstall

regsvr32 /u C:\Tools\NDSFileIcons.dll

Removes the per-user registration, and the machine-wide one when run elevated.

Test file

ok.nds is a minimal synthetic ROM (header + version 1 banner only). Its icon is a 4x4 grid of 8x8 tiles: transparent (top-left tile, palette color 0), red (top row, 2nd tile), green (2nd row, 2nd tile), blue (bottom-right), everything else black.

Troubleshooting

• Check the registration landed in the 64-bit view: reg query "HKCR\CLSID\{DF4F5AE4-E597-4C12-BC26-2776C27F71AE}\InprocServer32". If it only exists under WOW6432Node, a 32-bit DLL was registered.
• If an emulator owns .nds (a ProgID in HKCR\.nds or a UserChoice under HKCU\...\Explorer\FileExts\.nds), registration also adds the icon handler to that ProgID, backing up its DefaultIcon; unregister restores it. The emulator's "open" association is left alone. If the emulator is installed (or the default app changed) after registering, run regsvr32 again; ProgIDs bound by earlier registrations are kept and also restored on unregister.
• Shared ProgIDs are skipped: Applications\<exe> (created by "Open with -> Always") and AppX... (Store apps) cover several extensions at once. In that case the handler stays on .nds only, and the app's own icon may win.
• Files that are not valid ROMs (bad banner version or truncated banner) get the ProgID's original icon back (from the backup), or the default icon.
• A machine-wide (elevated) registration skips ProgIDs that also exist in HKCU\Software\Classes, since the per-user copy would shadow it. Register per user (regsvr32 /n /i:user ...) for those.
• An elevated Explorer ignores per-user (HKCU) registrations.

History

Project from 2011, last 32-bit version from 2012. Updated in 2026 for Windows 11: x64 build, VS 2022 toolset, per-user registration, debug code removed (c:\teste.ico, MessageBox) and the icon is now built directly as a 32bpp DIB at the size Explorer asks for, with palette color 0 transparent.

Based on http://www.codeproject.com/shell/ShellExtGuide9.asp written by: Michael Dunn (acidhelm@gmail.com) Release date: June 3, 2006