Create a Shell ContextMenu by right clicking on Desktop or Directory Background

Question

The .NET Shell extension framework called SharpShell is great; I've developed a right-click file Shell ContextMenu "quite easily" that works selecting both files and directories.

Now I would like to develop a Shell ContextMenu by righ-clicking on an empty space (that is, on the Desktop or on a white spot while I'm inside a folder). Is it possible do that still using SharpShell? Or do I need to move to a different solution?... and in 2nd case... what do you suggest?

Thanks

Answer 1

The two solutions presented below work, but in the meantime I have found that there is an easier solution that is actually already used in the samples that come with SharpShell.

See the CopyDirectoryLocationHandler class as an example of a context menu handler that is registered for the directory background (and the desktop):

[ComVisible(true)]
[COMServerAssociation(AssociationType.Class, @"Directory\Background")]
public class CopyDirectoryLocationHandler : SharpContextMenu
{
   // ...
}

If you want the handler to only handle clicks on the desktop background, use this code instead:

[ComVisible(true)]
[COMServerAssociation(AssociationType.Class, @"DesktopBackground")]
public class CopyDirectoryLocationHandler : SharpContextMenu
{
   // ...
}

---

Old obsolete answer:

You can use SharpShell for this purpose without problem. There are two possible approaches:

1. Register the Shell Extension to handle the folder background yourself

or

2. Modify SharpShell to handle the registration of the extension for the folder background for you.

---

Register the Shell Extension to handle the folder background yourself

Your shell extension is a COM server and as such is identified to the system via a GUID. This GUID is then used at places in the registry to register the COM extension for different purposes. When we manually want to register the extension for a purpose such as extending the context menu for folder backgrounds, it is best when our extension has a fixed GUID.

Currently your class looks like this:

 [ComVisible(true)]
 [COMServerAssociation(AssociationType.Directory)]
 public class MyContextMenuExtension : SharpContextMenu
 {

When compiling, the compiler will automatically generate a GUID to use for that class. But we can specify a specific one to use like this:

 [Guid("A75AFD0D-4A63-41E3-AAAA-AD08A574B8B0")]
 [ComVisible(true)]
 [COMServerAssociation(AssociationType.Directory)]
 public class MyContextMenuExtension : SharpContextMenu
 {

Do not use the same GUID as shown here but create your own unique one in Visual Studio via Menu Tools > Create GUID. Use a different GUID for every shell extension you write.

Then recompile the dll and install and register it again (using regasm or the SharpShell Server Manager tool.

Then create a text file named "registry.reg" with the following content (use your own specific GUID). Instead of "MyContextMenuExtension" specify the name of your extension.

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\Directory\Background\shellex\ContextMenuHandlers\MyContextMenuExtension]
@="{A75AFD0D-4A63-41E3-AAAA-AD08A574B8B0}"

Install the "registry.reg" file by double clicking. Your extension should now be active when you open the context menu for a folder background or the Desktop.

Instead of using the *.reg file, you can also make the changes manually using registry editor or if you have an installer instruct the installer to make those registry changes.

---

Modify SharpShell to handle the registration of the extension for the folder background for you

Make the following changes to the SharpShell source code:

In the file AssociationType.cs add a new enum value to the AssociationType enumeration:

  /// <summary>
  /// Create an association to the unknown files class.
  /// </summary>
  UnknownFiles,

  /// <summary>
  /// Create an association to the background of folders and the desktop
  /// </summary>
  DirectoryBackground

In the file ServerRegistrationManager.cs add a new private string constant:

/// <summary>
/// The 'directory' special class.
/// </summary>
private const string SpecialClass_Directory = @"Directory";

 /// <summary>
/// The 'directory background' special class.
/// </summary>
private const string SpecialClass_DirectoryBackground = @"Directory\Background";

Also in the file ServerRegistrationManager.cs in the method CreateClassNamesForAssociations in the big switch statement add a new case like this:

          case AssociationType.Directory:

               //  Return the directory class.
               return new[] { SpecialClass_Directory };

          case AssociationType.DirectoryBackground:

               //  Return the directory background class.
               return new[] { SpecialClass_DirectoryBackground };

Finally you only have to tell your own extension class to use this new enumeration value:

 [Guid("A75AFD0D-4A63-41E3-AAAA-AD08A574B8B0")]
 [ComVisible(true)]
 [COMServerAssociation(AssociationType.Directory)]
 [COMServerAssociation(AssociationType.DirectoryBackground)]
 public class MyContextMenuExtension : SharpContextMenu
 {