Explorer Bars

Explorer Bars, also known as command bands or toolbars, are a powerful UI element in Windows Explorer that allow for customizable functionality and user interaction within the main window. They can host a variety of controls, from simple buttons and text boxes to more complex views and data displays.

Introduction to Explorer Bars

Explorer bars are typically docked to the sides or top of the Explorer window, providing quick access to common actions, navigation, or information relevant to the current view. They are implemented as COM objects and integrate seamlessly with the Windows shell.

Key features include:

Customizable Content: Can host various UI elements.
Docking: Can be docked to different edges of the Explorer window.
Persistence: Settings and visibility can be saved.
Integration: Seamlessly part of the Windows Explorer interface.

Implementing an Explorer Bar

Creating a custom Explorer bar involves defining a COM object that implements specific interfaces, primarily ITravelBar and IExplorerBar.

Core Interfaces

ITravelBar: Manages the lifecycle and behavior of the bar within the navigation context.
IExplorerBar: Handles the visual representation and user interaction of the bar.

Registration

An Explorer bar must be registered in the Windows Registry under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Explorer Bars. This entry points to the CLSID of the COM object.

Example Registry Entry

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Explorer Bars\{YOUR-UNIQUE-CLSID}]
@="My Custom Explorer Bar"
"CLSID"="{YOUR-UNIQUE-CLSID}"

Note: GUIDs (Globally Unique Identifiers) are crucial for identifying your COM object. Ensure you generate a unique CLSID for your Explorer bar.

Common Explorer Bar Types

Windows provides several built-in Explorer bars, each serving a specific purpose:

History: Shows recently visited folders and pages.
Favorites: Provides quick access to saved favorite locations.
Links: Displays web links or shortcuts.
Search: Allows users to perform file system searches.
Details: Shows properties and details of the selected item.

Details Pane Example

The Details pane, typically shown at the bottom of an Explorer window, is a common example of an Explorer Bar functionality that displays information about selected files or folders.

Selected Item: MyDocument.docx

Type: Microsoft Word Document

Size: 1.2 MB

Date Modified: 2023-10-27 10:30 AM

Advanced Features and Considerations

When developing custom Explorer bars, consider the following:

Performance: Ensure your bar is lightweight and doesn't degrade Explorer's performance.
User Experience: Design an intuitive and responsive interface.
Compatibility: Test your bar on different Windows versions.
Security: Handle user data and system interactions responsibly.

Important: Modifying system components requires careful attention to detail. Always back up your system before making significant registry changes or deploying custom shell extensions.

Code Snippet: Getting the CLSID

Here's a conceptual example of how you might retrieve the CLSID of a registered Explorer bar:

// C++ Example (Conceptual)
#include <windows.h>
#include <objbase.h>
#include <atlbase.h> // For CComBSTR

// Assume your Explorer Bar's ProgID is "MyCompany.MyExplorerBar"
LPCTSTR pszProgID = _T("MyCompany.MyExplorerBar");
CLSID clsid;

HRESULT hr = CLSIDFromProgID(pszProgID, &clsid);

if (SUCCEEDED(hr)) {
    // Successfully retrieved CLSID
    TCHAR szCLSID[64];
    StringFromGUID2(clsid, szCLSID, sizeof(szCLSID)/sizeof(TCHAR));
    // Use szCLSID
} else {
    // Failed to retrieve CLSID
}

Windows Shell UI