How can I programatically tell Windows taskbar to open (or close) a given toolbar?

I have written a toolbar that runs on the taskbar. Unfortunately, after it is installed, the user has to enable it manually. Is there a way to tell explorer to open (or close) a given toolbar?

I would like for the installer, NSIS, to turn on the toolbar when the installation is complete (I realize that a plugin would be necessary).

I also want to know if it's possible to automatically enable a toolbar for all users, for example in a corporate environment where multiple users would share a PC.

Solution

This CodeProject comment does it by simulating key presses
Vista+ has API to do this, with ShowDeskBand and HideDeskBand

Edit: This code can now Add a deskband object (from Pinvoke.net, and these two MSDN forum questions):

[ComImport]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
[Guid("4CF504B0-DE96-11D0-8B3F-00A0C911E8E5")]
public interface IBandSite
{
    [PreserveSig]
    uint AddBand([In, MarshalAs(UnmanagedType.IUnknown)] Object pUnkSite);
    [PreserveSig]
    void RemoveBand(uint dwBandID);
}


private uint AddDeskbandToTray(Guid Deskband)
{
    Guid IUnknown = new Guid("{00000000-0000-0000-C000-000000000046}");
    Guid ITrayBand = new Guid("{F60AD0A0-E5E1-45cb-B51A-E15B9F8B2934}");   
    Type TrayBandSiteService = Type.GetTypeFromCLSID(ITrayBand, true);
    IBandSite BandSite = Activator.CreateInstance(TrayBandSiteService) as IBandSite;
    object DeskbandObject = CoCreateInstance(Deskband, null, CLSCTX.CLSCTX_INPROC_SERVER, IUnknown);
    return BandSite.AddBand(DeskbandObject);
}

And, an example use:

Guid address_toolbar_guid = new Guid("{01E04581-4EEE-11D0-BFE9-00AA005B4383}");
uint band_id = AddDeskbandToTray(address_toolbar_guid);

It would make sense that a similar call to RemoveBand would also do the trick, but as of yet, I can't get that code to work. Another issue: the added deskband closes when the application that added it closes.