ShellMenu Component

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The ShellMenu component enables customizing Shell context menu items and commands.

Syntax

callback.CBFSShell.ShellMenu

Remarks

The ShellMenu component provides a simple way to create custom context menu items for any items selected in the Windows Shell. An application may add such menu items to perform global or item-specific operations when a user chooses the command in the context menu displayed by the Shell for the selected items.

The component communicates with the Windows Shell through a proxy DLL that is loaded by Explorer in order to add a custom menu item to context menus and handle invocation of that menu item. The set of modules included in this product is discussed in the Deployment Instructions.

Installation and Initialization

First, call the Install method to register the proxy DLL with the Windows Shell. Installation should be done at least once before using the library on a new system, but may be done several times to update the values of the ProxyPath and Scope properties.

component.Install();

Following the installation, any custom menu items that will be added to the Windows context menu must be registered in the Windows Registry. To do this, call the RegisterMenuItem method for each custom menu item.

component.RegisterMenuItem("MyMenuItem");

The next step is to call Initialize, which will perform the necessary operations to facilitate communication between the system and your code. Initialization only needs to be called once per application launch.

component.Initialize();

Adding Menu Items

Call the Activate method to start serving context menu items and begin handling requests from the Windows Shell. After calling Activate, the MenuItems collection will be populated with the previously registered menu items.

component.Activate(); // If activation was successful this prints out "MyMenuItem" Console.WriteLine(component.MenuItems[0].Verb);

The Windows Registry only stores the unique text identifiers, or verbs, of the added menu items. As such, their additional properties, such as captions and icons are initialized to their default values every time the MenuItems collection is populated. To customize these properties, they must be set manually after calling the Activate method, or by handling the UpdateMenu event. For example:

component.OnUpdateMenu += (s, e) => { int itemCount = 0; foreach (MenuItem item in component.MenuItems) { if (item != null) { item.Caption = "Menu item #" + itemCount; item.Icon = "shell32.dll,-249"; // icon resource string included with the Windows Shell itemCount++; } } };

Once the component is activated, the menu items from the MenuItems collection will appear in the File-Explorer's right-click context menu for any selected Windows Shell items.

Note: Menu items may not be visible in the context menu if their caption property is set to an empty string.

When a user clicks on a context menu item, the InvokeMenu event is fired, and the SelectedItems collection is populated with the Windows Shell items selected in Windows File Explorer. An application may use the context provided by the SelectedItems collection to perform actions specifically tailored to the user's selections. For example:

component.OnInvokeMenu += (s, e) => { if (e.Verb.Equals("MyMenuItem")) { Console.WriteLine("Selected items: "); for (int i = 0; i < component.SelectedItems.Count; i++) { SelectedItem item = component.SelectedItems[i]; Console.WriteLine(item.FileName); } } };

Deactivation and Uninstall

To stop handling Windows Shell requests and render all custom menu items inactive, call the Deactivate method.

component.Deactivate();

Since the menu items registered via the RegisterMenuItem method are not automatically removed from the Windows Registry, it is recommended to call UnregisterMenuItem to unregister each menu item individually during the application's uninstall routine.

component.UnregisterMenuItem("MyMenuItem");

Finally, to detach the component from the Windows Shell and unregister the proxy DLL from the system, call the Uninstall method. Normally, this is done when the application is removed from the system.

component.Uninstall();

PIDLs

A PIDL (or an IDL) is a fundamental Windows Shell concept. At a high level, it is pretty simple, as it is just a value that represents a Windows Shell item in the Windows Shell Namespace. It is a bit like a full filesystem path for a physical file or folder, except that it is a binary object and not a string. The name "PIDL" and "IDL" can be used interchangeably. The leading P stands for pointer, the IDL stands for item identifier list, and PIDL generally refers to an IDL itself rather than the pointer to it.

The below information is provided as a general knowledge. Your application will deal with PIDLs only when they denote some Windows Shell items that are not necessarily a part of the Windows Shell namespace extension that you create. Such PIDLs can be used with the Windows Shell API if you decide to call it directly. When CBFS Shell exposes these PIDL values they will appear hex-encoded. If an application needs to call a shell function, it has to decode the PIDL before calling that function.

Just like a full filesystem path is a list of strings separated by the directory separator (on Windows, it is the \ (backslash) character), a PIDL is a list (L is for list) of Ids (identifiers). Unlike a filesystem path, though, a PIDL is binary, and Ids are separated by a special PIDL separator (two consecutive zero bytes).

Microsoft provides more details about PIDLs here Identifying Namespace Objects.

Troubleshooting

Following are some helpful resources for troubleshooting issues related to the display of menu items.

• If you are developing your application and you stop and start repeatedly while keeping Windows File Explorer open, there may be a memory/cache issue. To avoid this situation one should terminate Explorer and reopen it.
• If your context menu items do not appear at all or an excess number of menu items appear, this may indicate a registration/deregistration issue. Try running the application with administrative privileges.
• If you are seeing strange behavior not contained in this list, please reach out to us with a description of the problem and we are happy to help. Our support team is available over email at support@callback.com

Property List

The following is the full list of the properties of the component with short descriptions. Click on the links for further details.

Method List

The following is the full list of the methods of the component with short descriptions. Click on the links for further details.

Event List

The following is the full list of the events fired by the component with short descriptions. Click on the links for further details.

Config Settings

The following is a list of config settings for the component with short descriptions. Click on the links for further details.

MenuItems Property (ShellMenu Component)

This property contains a collection of registered menu items.

Syntax

• C#
• VB.NET

public MenuItemList MenuItems { get; }

Public ReadOnly Property MenuItems As MenuItemList

Remarks

This property holds a collection of MenuItem objects.

Customizing Menu Items

Note: Registered menu items may not appear in the context menu if their Caption property is set to an empty string.

This property is read-only and not available at design time.

ProxyPath Property (ShellMenu Component)

This property specifies the path to the native proxy DLL.

Syntax

• C#
• VB.NET

public string ProxyPath { get; set; }

Public Property ProxyPath As String

Default Value

""

Remarks

This property may be used to specify the full path with the name of the native proxy DLL, which is loaded by the Windows Shell.

If left empty, the component will automatically attempt to locate the appropriate DLL by searching the directory where the application's executable resides.

Scope Property (ShellMenu Component)

This property specifies whether the component is registered for the current user or for all users.

Syntax

• C#
• VB.NET

public ShellMenuScopes Scope { get; set; }

enum ShellMenuScopes {
  isAllUsers,
  isCurrentUser
}

Public Property Scope As ShellmenuScopes

Enum ShellMenuScopes
  isAllUsers
  isCurrentUser
End Enum

Default Value

1

Remarks

This property specifies whether the information related to the component is written to the registry for the current user or for all users.

In the latter case, administrative rights are required to successfully execute the Install and Uninstall methods. If the user account of the process that calls these methods does not have such rights, the call will fail with an error.

SelectedItems Property (ShellMenu Component)

This property contains a collection of selected Windows Shell items.

Syntax

• C#
• VB.NET

public SelectedItemList SelectedItems { get; }

Public ReadOnly Property SelectedItems As SelectedItemList

Remarks

This property holds a collection of SelectedItem objects, which is populated when a menu is invoked or clicked.

This property is read-only and not available at design time.

Activate Method (ShellMenu Component)

This method tells the component to start handling the requests sent to the namespace extension.

Syntax

• C#
• VB.NET

public void Activate();

Public Sub Activate()

Remarks

This method is used to tell the component to begin handling Windows Shell requests and start firing the corresponding events.

Customizing Menu Items

Note: Registered menu items may not appear in the context menu if their Caption property is set to an empty string.

Menu Item Persistence

Config Method (ShellMenu Component)

This method sets or retrieves a configuration setting.

Syntax

• C#
• VB.NET

public string Config(string configurationString);

Public Function Config(ByVal ConfigurationString As String) As String

Remarks

Config is a generic method available in every component. It is used to set and retrieve configuration settings for the component.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the component, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

Deactivate Method (ShellMenu Component)

This method tells the component to stop handling the requests sent to the namespace extension.

Syntax

• C#
• VB.NET

public void Deactivate();

Public Sub Deactivate()

Remarks

This method tells the component to stop handling Windows Shell requests and stop firing the corresponding events.

Initialize Method (ShellMenu Component)

This method initializes the core library.

Syntax

• C#
• VB.NET

public void Initialize();

Public Sub Initialize()

Remarks

This method initializes the core library and must be called each time the application starts before attempting to use other component's methods. The only exceptions to this are Install, Uninstall, RegisterMenuItem, and UnregisterMenuItem.

If the application explicitly specifies the path to the proxy DLL, it should do this through the ProxyPath property before calling this method.

Install Method (ShellMenu Component)

This method registers context menu information to the system.

Syntax

• C#
• VB.NET

public void Install();

Public Sub Install()

Remarks

This method is used to install the native proxy DLL that integrates with the Windows Shell.

Before calling this method, you may change the default values of the ProxyPath, and Scope properties. These values are used during installation.

Registry Scope and User Permissions

In the latter case, administrative rights are required to execute this method successfully. If the user account of the process that calls this method does not have such rights, the call will fail with an ERROR_PRIVILEGE_NOT_HELD (0x0522) error.

RegisterMenuItem Method (ShellMenu Component)

This method adds a menu item to the Windows Registry.

Syntax

• C#
• VB.NET

public void RegisterMenuItem(string verb);

Public Sub RegisterMenuItem(ByVal Verb As String)

Remarks

This method registers a menu item to the Windows Registry. Menu items must be registered before they can be used in a context menu. Normally, this is only needs to be done once during application installation.

The Verb parameter specifies a unique text identifier of the context menu item. This is the only aspect of the menu item that gets stored in the Windows Registry.

Windows Registry Pollution

Customizing Menu Items

Note: Registered menu items may not appear in the context menu if their Caption property is set to an empty string.

Registry Scope and User Permissions

In the latter case, administrative rights are required to execute this method successfully. If the user account of the process that calls this method does not have such rights, the call will fail with an ERROR_PRIVILEGE_NOT_HELD (0x0522) error.

Uninstall Method (ShellMenu Component)

This method unregisters context menu information from the system.

Syntax

• C#
• VB.NET

public void Uninstall();

Public Sub Uninstall()

Remarks

This method is used to uninstall the proxy DLL that integrates with the Windows Shell from the system.

Before calling this method, you may change the default value of the Scope property.

Windows Registry Pollution

Registry Scope and User Permissions

In the latter case, administrative rights are required to execute this method successfully. If the user account of the process that calls this method does not have such rights, the call will fail with an ERROR_PRIVILEGE_NOT_HELD (0x0522) error.

Handling Multiple Components

As ShellFolder and ShellMenu components share a proxy DLL and a product GUID, they store some common information in a registry key. Calling the Uninstall method of one of the components will delete a shared registry key as well.

Each component should be uninstalled properly by calling the corresponding Uninstall method. At the same time, if an application needs to uninstall just one component and keep the other(s), it should call the Uninstall method of that component and then call the Install method of the other components to restore the common information in the shared registry key.

UnregisterMenuItem Method (ShellMenu Component)

This method unregisters a previously registered menu item.

Syntax

• C#
• VB.NET

public void UnregisterMenuItem(string verb);

Public Sub UnregisterMenuItem(ByVal Verb As String)

Remarks

This method is used to remove a menu item that was registered with RegisterMenuItem from the Windows Registry. This should normally be done once per each menu item after the Uninstall method has been called.

The Verb parameter specifies the unique text identifier of the context menu item.

Registry Scope and User Permissions

In the latter case, administrative rights are required to execute this method successfully. If the user account of the process that calls this method does not have such rights, the call will fail with an ERROR_PRIVILEGE_NOT_HELD (0x0522) error.

Error Event (ShellMenu Component)

This event is fired if an unhandled error occurs during an event.

Syntax

• C#
• VB.NET

public event OnErrorHandler OnError;

public delegate void OnErrorHandler(object sender, ShellMenuErrorEventArgs e);

public class ShellMenuErrorEventArgs : EventArgs {
  public int ErrorCode { get; }
  public string Description { get; }
}

Public Event OnError As OnErrorHandler

Public Delegate Sub OnErrorHandler(sender As Object, e As ShellMenuErrorEventArgs)

Public Class ShellMenuErrorEventArgs Inherits EventArgs
  Public ReadOnly Property ErrorCode As Integer
  Public ReadOnly Property Description As String
End Class

Remarks

This event fires if an unhandled error occurs. Developers can use this information to track down unhandled errors that occur in the component.

ErrorCode contains an error code and Description contains a textual description of the error.

InvokeMenu Event (ShellMenu Component)

This event is fired when an item of the context menu is invoked.

Syntax

• C#
• VB.NET

public event OnInvokeMenuHandler OnInvokeMenu;

public delegate void OnInvokeMenuHandler(object sender, ShellMenuInvokeMenuEventArgs e);

public class ShellMenuInvokeMenuEventArgs : EventArgs {
  public string Verb { get; }
  public long Context { get; }
}

Public Event OnInvokeMenu As OnInvokeMenuHandler

Public Delegate Sub OnInvokeMenuHandler(sender As Object, e As ShellMenuInvokeMenuEventArgs)

Public Class ShellMenuInvokeMenuEventArgs Inherits EventArgs
  Public ReadOnly Property Verb As String
  Public ReadOnly Property Context As Long
End Class

Remarks

This event is fired when a user invokes, or clicks on, a context menu item that has been registered with RegisterMenuItem. To obtain the list of the Windows Shell items for which the context menu was displayed, use the SelectedItems property.

The Verb parameter contains the unique text identifier of the menu item that was invoked.

The Context parameter is a unique identifier that remains the same across multiple event calls for the same operation. Since the event may fire multiple times for the same operation, its value may be used to avoid performing the same tasks more than once.

UI Considerations

var thread = new Thread(() => { ... } // "..." is the code that an event handler executes in a helper thread thread.SetApartmentState(ApartmentState.STA); thread.IsBackground = true; thread.Start(); thread.Join(); // optional, if your code should work synchronously

UpdateMenu Event (ShellMenu Component)

This event is fired when the context menu needs to be updated.

Syntax

• C#
• VB.NET

public event OnUpdateMenuHandler OnUpdateMenu;

public delegate void OnUpdateMenuHandler(object sender, ShellMenuUpdateMenuEventArgs e);

public class ShellMenuUpdateMenuEventArgs : EventArgs {
  public string Verb { get; }
  public long Context { get; }
}

Public Event OnUpdateMenu As OnUpdateMenuHandler

Public Delegate Sub OnUpdateMenuHandler(sender As Object, e As ShellMenuUpdateMenuEventArgs)

Public Class ShellMenuUpdateMenuEventArgs Inherits EventArgs
  Public ReadOnly Property Verb As String
  Public ReadOnly Property Context As Long
End Class

Remarks

This event is fired when the system needs to update the context menu before it is displayed. The event fires separately for each menu item that was registered via RegisterMenuItem. An event handler is expected to update the menu item in the MenuItems collection if such an update is required, and such updates will be reflected in the displayed menu. To obtain the list of Windows Shell items for which the context menu is about to be displayed, use the SelectedItems property.

The Verb parameter contains the unique text identifier of the corresponding menu item that may be updated.

The Context parameter is a unique identifier that remains the same across multiple event calls for the same operation. Since the event may fire multiple times for the same operation, its value may be used to avoid performing the same tasks more than once.

UI Considerations

var thread = new Thread(() => { ... } // "..." is the code that an event handler executes in a helper thread thread.SetApartmentState(ApartmentState.STA); thread.IsBackground = true; thread.Start(); thread.Join(); // optional, if your code should work synchronously

MenuItem Type

Represents a registered menu item.

Remarks

This type represents a registered menu item.

Fields

SelectedItem Type

Represents a selected Windows Shell item.

Remarks

This type represents a Windows Shell item in the list of items selected in ShellMenu.

Fields

Config Settings (ShellMenu Component)

ShellMenu Config Settings

Base Config Settings

Trappable Errors (ShellMenu Component)

ShellMenu Errors