UniversalShellExt

Generic COM Shell Extension for Windows that adds a customizable entry to the folder context menu.

Features

• ✅ Customizable Context Menu:
  • Context menu entry for folders (right-click on folder)
  • Context menu entry for folder background (right-click on empty area)
  • Text, icon and command fully configurable via registry
• ✅ Flexible Configuration:
  • All parameters read from the Windows registry
  • Support for custom arguments with %1 placeholder
  • Icon automatically extracted from the executable
• ✅ Security and Compatibility:
  • Automatic UAC elevation support when required
  • Compatible with Windows 10/11 (x64)
  • Correct WOW64 registry access (64-bit)
  • Thread-safe

Project Files

File	Description
UniversalShellExt.cpp	C++ source code of the COM Shell Extension
UniversalShellExt.def	DLL export definitions
UniversalShellExt.rc	DLL resources (Version Info)
build.py	Python script for build, signing and registration

Configuration

The DLL reads its configuration from the Windows registry:

Registry Keys

Path: HKEY_LOCAL_MACHINE\SOFTWARE\UniversalShellExt

(Fallback: HKEY_CURRENT_USER\SOFTWARE\UniversalShellExt)

Value	Type	Description	Example
Command	REG_SZ	Full path to the executable	N:\VSCode.exe
Arguments	REG_SZ	Arguments to pass (%1 = selected path)	"%1"
MenuText	REG_SZ	Text displayed in the menu	Open with VSCode
Icon	REG_SZ	Icon path (exe or ico)	N:\VSCode.exe

Configuration Template

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\UniversalShellExt]
"Command"="N:\\VSCode.exe"
"Arguments"="\"%1\""
"MenuText"="Open with VSCode Portable"
"Icon"="N:\\VSCode.exe"

Default Values

If not configured:

• Arguments → "%1" (passes the selected path)
• MenuText → "Open with Application"
• Icon → uses the same path as Command

Identifiers

Type	Value
CLSID	{5D849F86-F2A9-41FA-8A24-E01CD6D6696C}
COM Name	Universal Portable Shell Extension

Build

Prerequisites

• Visual Studio 2022 (with "Desktop development with C++" workload)
• Windows SDK (for signtool.exe and rc.exe)
• Python 3.x
• Signing certificate (optional, for digital signing)

Build Script

# Full build (compile, copy, sign, register)
python build.py

# Clean only
python build.py --clean

# Unregister only
python build.py --unregister

# Build without signing
python build.py --no-sign

Output

The compiled DLL is copied to:

plugins\UniversalShellExt64.dll

Registration

Recommended Method (via Launcher)

The VSCode.exe launcher automatically manages registration:

N:\VSCode.exe /register           # Register the shell extension
N:\VSCode.exe /unregister         # Remove the shell extension
N:\VSCode.exe /register /silent   # Silent mode

Manual Method (regsvr32)

Run as Administrator:

regsvr32 "plugins\UniversalShellExt64.dll"

Registry Keys Created

During registration (DllRegisterServer):

Key	Purpose
HKCR\CLSID\{5D849F86-...}	COM class registration
HKCR\CLSID\{5D849F86-...}\InprocServer32	DLL path
HKCR\Directory\shellex\ContextMenuHandlers\UniversalShellExt	Handler for folders
HKCR\Directory\Background\shellex\ContextMenuHandlers\...	Handler for folder background
HKLM\...\Shell Extensions\Approved	Microsoft whitelist

How It Works

1. Initialization: When the user right-clicks, Explorer loads the DLL
2. Configuration: The DLL reads Command, Arguments, MenuText, Icon from the registry
3. Menu: Inserts the entry in the context menu with the configured icon
4. Execution: On click, replaces %1 with the path and launches the command
5. UAC: If the command requires elevation, requests it automatically

Troubleshooting

Entry does not appear in the menu

1. Verify the DLL is registered (regsvr32)
2. Check that the registry keys are configured
3. Restart Explorer (taskkill /F /IM explorer.exe && explorer.exe)

Registration error

• Run as Administrator
• Verify the DLL is signed (Windows may block unsigned DLLs)

Command is not executed

• Verify the path in Command is correct
• Check that Arguments contains %1 to receive the path

Versions

Version	Notes
1.0.0	First release — generic shell extension configurable via registry

License

Internal use — emulab.it

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See README_IT.md for the Italian version.