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How to programmatically activate a band object

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This article was previously published under Q255920

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Summary

The only supported way to programmatically show and hide a band object (such as an Explorer Bar, CommBand, or ToolBand) in Internet Explorer is to use the IWebBrowser2::ShowBrowserBar method.

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More information

In many cases, developers of band objects want to be able to automatically display their band object when the user starts a new instance of Internet Explorer. The best way to achieve this functionality is to use a Browser Helper Object (BHO) in conjunction with the band object. In this way, the BHO can decide whether or not to programmatically activate the band object based on registry keys or other settings persisted by the band object itself.

To build a minimal BHO that can programmatically activate a band object (the Search bar, in this example), you can create a new ATL/COM AppWizard project and add a new Internet Explorer object. Then, override IObjectWithSite::SetSite to achieve the desired functionality. The new SetSite implementation should look as follows: 
STDMETHODIMP CShowBarObj::SetSite(IUnknown *pUnkSite)
{
   if (NULL != pUnkSite)
   {
      IWebBrowser2 *pBrowser = NULL;
      // Ensure that our site is an browser window
      HRESULT hr = pUnkSite->QueryInterface(IID_IWebBrowser2, (void **) &pBrowser);
      if (SUCCEEDED(hr))
      {
         // Display the band object (the Search bar in this case)
         VARIANT vtBandGUID, vtShow;
         vtBandGUID.vt = VT_BSTR;
         vtBandGUID.bstrVal = SysAllocString(OLESTR("{30D02401-6A81-11D0-8274-00C04FD5AE38}"));
         vtShow.vt = VT_BOOL;
         vtShow.boolVal = true;
         pBrowser->ShowBrowserBar(&vtBandGUID, &vtShow, 0);
         SysFreeString(vtBandGUID.bstrVal);
         pBrowser->Release();
      }
   }
   return S_OK;
}
Also, you must include the header file ExDisp.h in the code and append the following code to the RGS file used for DLL self-registration. Note that you must replace "{77D54ACE-09A9-11D4-8ACE-00C04F542830}" with the CLSID of your BHO: 
HKLM { 
   SOFTWARE { 
      Microsoft { 
         Windows { 
            CurrentVersion { 
               Explorer { 
                  'Browser Helper Objects' {
                         {77D54ACE-09A9-11D4-8ACE-00C04F542830}
                            } 
                        } 
                    } 
                } 
            } 
        } 
    }

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Keywords: KB255920, kbhowto, kbbandobjs

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Article Info
Article ID : 255920
Revision : 5
Created on : 7/15/2004
Published on : 7/15/2004
Exists online : False
Views : 462