C# Signature:

[ComImportAttribute()]
[GuidAttribute("c43dc798-95d1-4bea-9030-bb99e2983a1a")]
[InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)]
internal interface ITaskbarList4
{
     // ITaskbarList
     [PreserveSig]
     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);
}