Add browser action button in internet explorer BHO

Question

So. I'm working on a BHO in IE and I want to add a browser action like this: In internet explorer it would look something like The only tutorials and docs I've found were on creating toolbar items. None mentioned this option. I know this is possible because crossrider let you do this exact thing. I just don't know how. I can't find any documentation on how I would implement this in a BHO. Any pointers are very welcome. I tagged this with C# as a C# solution would probably be simpler but a C++ solution, or any other solution that works is also very welcome.

Accepted Answer

EDIT: https://github.com/somanuell/SoBrowserAction

Here is a screen shot of my work in progress.

The things I did:

1. Escaping from the protected mode

The BHO Registration must update the `HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Low Rights\ElevationPolicy` key. See Understanding and Working in Protected Mode Internet Explorer.

I choose the process way because it's noted as "best practice" and is easier to debug, but the `RunDll32Policy` may do the trick, too.

Locate the `rgs` file containing your BHO registry settings. It's the one containing the upadte to the Registry Key `'Browser Helper Object'`. Add to that file the following:

```
HKLM {
  NoRemove SOFTWARE {
    NoRemove Microsoft {
      NoRemove 'Internet Explorer' {
        NoRemove 'Low Rights' {
          NoRemove ElevationPolicy {
            ForceRemove '{AE6E5BFE-B965-41B5-AC70-D7069E555C76}' {
              val AppName = s 'SoBrowserActionInjector.exe'
              val AppPath = s '%MODULEPATH%'
              val Policy = d '3'
            }
          }
        }
      }
    }
  }
}
```

The GUID must be a new one, don't use mine, use a GUID Generator. The `3` value for policy ensures that the broker process will be launched as a medium integrity process. The `%MODULEPATH%`macro is NOT a predefined one.

Why use a macro? You may avoid that new code in your RGS file, provided that your MSI contains that update to the registry. As dealing with MSI may be painful, it's often easier to provide a "full self registering" package. But if you don't use a macro, you then can't allow the user to choose the installation directory. Using a macro permits to dynamically update the registry with the correct installation directory.

How to make the macro works? Locate the `DECLARE_REGISTRY_RESOURCEID` macro in the header of your BHO class and comment it out. Add the following function definition in that header:

```
static HRESULT WINAPI UpdateRegistry( BOOL bRegister ) throw() {
   ATL::_ATL_REGMAP_ENTRY regMapEntries[2];
   memset( &regMapEntries[1], 0, sizeof(ATL::_ATL_REGMAP_ENTRY));
   regMapEntries[0].szKey = L"MODULEPATH";
   regMapEntries[0].szData = sm_szModulePath;
   return ATL::_pAtlModule->UpdateRegistryFromResource(IDR_CSOBABHO, bRegister,
                                                       regMapEntries);
}
```

That code is borrowed from the ATL implementation for `DECLARE_REGISTRY_RESOURCEID` (in my case it's the one shipped with VS2010, check your version of ATL and update code if necessary). The `IDR_CSOBABHO` macro is the resource ID of the `REGISTRY` resource adding the RGS in your RC file.

The `sm_szModulePath` variable must contains the installation path of the broker process EXE. I choose to make it a public static member variable of my BHO class. One simple way to set it up is in the `DllMain` function. When `regsvr32` load your Dll, `DllMain` is called, and the registry is updated with the good path.

```
extern "C" BOOL WINAPI DllMain(HINSTANCE hInstance, DWORD dwReason, LPVOID lpReserved) {

if ( dwReason == DLL_PROCESS_ATTACH ) {
      DWORD dwCopied = GetModuleFileName( hInstance,
                                          CCSoBABHO::sm_szModulePath,
                                          sizeof( CCSoBABHO::sm_szModulePath ) /
                                                        sizeof( wchar_t ) );
      if ( dwCopied ) {
         wchar_t * pLastAntiSlash = wcsrchr( CCSoBABHO::sm_szModulePath, L'\' );
         if ( pLastAntiSlash ) *( pLastAntiSlash ) = 0;
      }
   }

return _AtlModule.DllMain(dwReason, lpReserved);

}
```

Many thanks to Mladen Janković.

How to lauch the Broker process?

One possible place is in the `SetSite` implementation. It will be lauched many times, but we will deal with that in the process itself. We will see later that the broker process may benefit from receiving as argument the HWND for the hosting IEFrame. This can be done with the `IWebBrowser2::get_HWND` method. I suppose here that your already have an `IWebBrowser2*` member.

```
STDMETHODIMP CCSoBABHO::SetSite( IUnknown* pUnkSite ) {

if ( pUnkSite ) {
      HRESULT hr = pUnkSite->QueryInterface( IID_IWebBrowser2, (void**)&m_spIWebBrowser2 );
      if ( SUCCEEDED( hr ) && m_spIWebBrowser2 ) {
         SHANDLE_PTR hWndIEFrame;
         hr = m_spIWebBrowser2->get_HWND( &hWndIEFrame );
         if ( SUCCEEDED( hr ) ) {
            wchar_t szExeName[] = L"SoBrowserActionInjector.exe";
            wchar_t szFullPath[ MAX_PATH ];
            wcscpy_s( szFullPath, sm_szModulePath );
            wcscat_s( szFullPath, L"\" );
            wcscat_s( szFullPath, szExeName );
            STARTUPINFO si;
            memset( &si, 0, sizeof( si ) );
            si.cb = sizeof( si );
            PROCESS_INFORMATION pi;
            wchar_t szCommandLine[ 64 ];
            swprintf_s( szCommandLine, L"%.48s %d", szExeName, (int)hWndIEFrame );
            BOOL bWin32Success = CreateProcess( szFullPath, szCommandLine, N…

Add browser action button in internet explorer BHO

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