C# Signature:

[ComImportAttribute()]
[GuidAttribute("c43dc798-95d1-4bea-9030-bb99e2983a1a")]
[InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)]
internal interface ITaskbarList4
[ComImport,
Guid("56fdf342-fd6d-11d0-958a-006097c9a090"),
InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface ITaskbarList
{
     // ITaskbarList
     [PreserveSig]
     /// <summary>
     /// Initializes the taskbar list object. This method must be called before any other ITaskbarList methods can be called.
     /// </summary>
     void HrInit();
     [PreserveSig]
     void AddTab(IntPtr hwnd);
     [PreserveSig]
     void DeleteTab(IntPtr hwnd);
     [PreserveSig]
     void ActivateTab(IntPtr hwnd);
     [PreserveSig]
     void SetActiveAlt(IntPtr hwnd);

     // ITaskbarList2
     [PreserveSig]
     void MarkFullscreenWindow(
     IntPtr hwnd,
     [MarshalAs(UnmanagedType.Bool)] bool fFullscreen);

     // ITaskbarList3
     [PreserveSig]
     void SetProgressValue(IntPtr hwnd, UInt64 ullCompleted, UInt64 ullTotal);
     [PreserveSig]
     void SetProgressState(IntPtr hwnd, TaskbarProgressBarStatus tbpFlags);
     [PreserveSig]
     void RegisterTab(IntPtr hwndTab, IntPtr hwndMDI);
     [PreserveSig]
     void UnregisterTab(IntPtr hwndTab);
     [PreserveSig]
     void SetTabOrder(IntPtr hwndTab, IntPtr hwndInsertBefore);
     [PreserveSig]
     void SetTabActive(IntPtr hwndTab, IntPtr hwndInsertBefore, uint dwReserved);
     [PreserveSig]
     HResult ThumbBarAddButtons(
     IntPtr hwnd,
     uint cButtons,
     [MarshalAs(UnmanagedType.LPArray)] ThumbButton[] pButtons);
     [PreserveSig]
     HResult ThumbBarUpdateButtons(
     IntPtr hwnd,
     uint cButtons,
     [MarshalAs(UnmanagedType.LPArray)] ThumbButton[] pButtons);
     [PreserveSig]
     void ThumbBarSetImageList(IntPtr hwnd, IntPtr himl);
     [PreserveSig]
     void SetOverlayIcon(
       IntPtr hwnd,
       IntPtr hIcon,
       [MarshalAs(UnmanagedType.LPWStr)] string pszDescription);
     [PreserveSig]
     void SetThumbnailTooltip(
     IntPtr hwnd,
     [MarshalAs(UnmanagedType.LPWStr)] string pszTip);
     [PreserveSig]
     void SetThumbnailClip(
     IntPtr hwnd,
     IntPtr prcClip);

     // ITaskbarList4
     void SetTabProperties(IntPtr hwndTab, SetTabPropertiesOption stpFlags);
}

VB Signature:

<ComImportAttribute> _
<GuidAttribute("c43dc798-95d1-4bea-9030-bb99e2983a1a")> _
<InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)> _
Friend Interface ITaskbarList4
    ' ITaskbarList
    <PreserveSig> _
    Sub HrInit()
    <PreserveSig> _
    Sub AddTab(hwnd As IntPtr)
    <PreserveSig> _
    Sub DeleteTab(hwnd As IntPtr)
    <PreserveSig> _
    Sub ActivateTab(hwnd As IntPtr)
    <PreserveSig> _
    Sub SetActiveAlt(hwnd As IntPtr)

    ' ITaskbarList2
    <PreserveSig> _
    Sub MarkFullscreenWindow(hwnd As IntPtr, <MarshalAs(UnmanagedType.Bool)> fFullscreen As Boolean)
     /// <summary>
     /// Adds an item to the taskbar.
     /// </summary>
     /// <param name="hWnd">A handle to the window to be added to the taskbar.</param>
     void AddTab([In] IntPtr hWnd);

    ' ITaskbarList3
    <PreserveSig> _
    Sub SetProgressValue(hwnd As IntPtr, ullCompleted As UInt64, ullTotal As UInt64)
    <PreserveSig> _
    Sub SetProgressState(hwnd As IntPtr, tbpFlags As TaskbarProgressBarStatus)
    <PreserveSig> _
    Sub RegisterTab(hwndTab As IntPtr, hwndMDI As IntPtr)
    <PreserveSig> _
    Sub UnregisterTab(hwndTab As IntPtr)
    <PreserveSig> _
    Sub SetTabOrder(hwndTab As IntPtr, hwndInsertBefore As IntPtr)
    <PreserveSig> _
    Sub SetTabActive(hwndTab As IntPtr, hwndInsertBefore As IntPtr, dwReserved As UInteger)
    <PreserveSig> _
    Function ThumbBarAddButtons(hwnd As IntPtr, cButtons As UInteger, <MarshalAs(UnmanagedType.LPArray)> pButtons As ThumbButton()) As HResult
    <PreserveSig> _
    Function ThumbBarUpdateButtons(hwnd As IntPtr, cButtons As UInteger, <MarshalAs(UnmanagedType.LPArray)> pButtons As ThumbButton()) As HResult
    <PreserveSig> _
    Sub ThumbBarSetImageList(hwnd As IntPtr, himl As IntPtr)
    <PreserveSig> _
    Sub SetOverlayIcon(hwnd As IntPtr, hIcon As IntPtr, <MarshalAs(UnmanagedType.LPWStr)> pszDescription As String)
    <PreserveSig> _
    Sub SetThumbnailTooltip(hwnd As IntPtr, <MarshalAs(UnmanagedType.LPWStr)> pszTip As String)
    <PreserveSig> _
    Sub SetThumbnailClip(hwnd As IntPtr, prcClip As IntPtr)
     /// <summary>
     /// Deletes an item from the taskbar.
     /// </summary>
     /// <param name="hWnd">A handle to the window to be deleted from the taskbar.</param>
     void DeleteTab([In] IntPtr hWnd);

    ' ITaskbarList4
    Sub SetTabProperties(hwndTab As IntPtr, stpFlags As SetTabPropertiesOption)
End Interface

User-Defined Types:

Do you know one? Please contribute it!

     /// <summary>
     /// Activates an item on the taskbar. The window is not actually activated; the window's item on the taskbar is merely displayed as active.
     /// </summary>
     /// <param name="hWnd">A handle to the window on the taskbar to be displayed as active.</param>
     void ActivateTab([In] IntPtr hWnd);

Alternative Managed API:

Do you know one? Please contribute it!

     /// <summary>
     /// Marks a taskbar item as active but does not visually activate it.
     /// </summary>
     /// <param name="hWnd">A handle to the window to be marked as active.</param>
     void SetActiveAlt([In] IntPtr hWnd);
}

Notes:

None.

[ComImport]
[Guid("56fdf344-fd6d-11d0-958a-006097c9a090")]
public class CoTaskbarList
{
}

VB Signature:

Declare Function ITaskbarList Lib "shell32.dll" (TODO) As TODO

Tips & Tricks:

Please add some!

Sample Code:

Please add some!

Documentation

ITaskbarList4 on MSDN

VB.NET full Implementation:

Since I wanted this to work on x64 and x86 Plattforms I used the IntPtr based approach.

It works perfect using Windows7 (64) - in WinXP the Taskbar-Items tend to reappear after a while after hiding them.

Don't forget to Import System.Runtime.CompilerServices and System.Runtime.InteropServices

    <ComImport, TypeLibType(CShort(2)), Guid("56FDF344-FD6D-11D0-958A-006097C9A090"), ClassInterface(CShort(0))> _
    Public Class TaskbarListClass
    Implements ITaskbarList, TaskbarList
    ' Methods
    <MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)> _
    Public Sub New()
    End Sub

    <MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)> _
    Public Overridable Sub ActivateTab(<[In]> ByVal hwnd As IntPtr) Implements ITaskbarList.ActivateTab
    End Sub

    <MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)> _
    Public Overridable Sub AddTab(<[In]> ByVal hwnd As IntPtr) Implements ITaskbarList.AddTab
    End Sub

    <MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)> _
    Public Overridable Sub DeleteTab(<[In]> ByVal hwnd As IntPtr) Implements ITaskbarList.DeleteTab
    End Sub

    <MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)> _
    Public Overridable Sub HrInit() Implements ITaskbarList.HrInit
    End Sub

    <MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)> _
    Public Overridable Sub SetActivateAlt(<[In]> ByVal hwnd As IntPtr) Implements ITaskbarList.SetActivateAlt
        End Sub
    End Class

    <ComImport, Guid("56FDF342-FD6D-11D0-958A-006097C9A090"), CoClass(GetType(TaskbarListClass))> _
    Public Interface TaskbarList
    Inherits ITaskbarList
    End Interface

    <ComImport, InterfaceType(CShort(1)), Guid("56FDF342-FD6D-11D0-958A-006097C9A090")> _
    Public Interface ITaskbarList
    <MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)> _
    Sub HrInit()
    <MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)> _
    Sub AddTab(<[In]> ByVal hwnd As IntPtr)
    <MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)> _
    Sub DeleteTab(<[In]> ByVal hwnd As IntPtr)
    <MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)> _
    Sub ActivateTab(<[In]> ByVal hwnd As IntPtr)
    <MethodImpl(MethodImplOptions.InternalCall, MethodCodeType:=MethodCodeType.Runtime)> _
    Sub SetActivateAlt(<[In]> ByVal hwnd As IntPtr)
    End Interface

User-Defined Types:

None.

Alternative Managed API:

http://code.msdn.microsoft.com/WindowsAPICodePack

Notes:

None.

Tips & Tricks:

Please add some!

Sample Code:

IntPtr windowHandle = ...;
var taskbarList = (ITaskbarList) new CoTaskbarList();
taskbarList.HrInit();
taskbarList.DeleteTab(windowHandle);

Documentation

ITaskbarList on MSDN

http://msdn.microsoft.com/en-us/library/bb774652(VS.85).aspx

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