Windows 7 Taskbar SetOverlayIcon from WPF app doesn't work

Question

I\'m trying to use the Windows 7 Taskbar API to set the overlay icon of the application icon on the taskbar.

I\'ve downloaded the samples from Microsoft, but wanted

Answer 1

Your ITaskBarList3 interface is wrong. Here the correct one:

public enum TBPF
{
    TBPF_NOPROGRESS = 0,
    TBPF_INDETERMINATE = 0x1,
    TBPF_NORMAL = 0x2,
    TBPF_ERROR = 0x4,
    TBPF_PAUSED = 0x8
}

public enum TBATF
{
    TBATF_USEMDITHUMBNAIL = 0x1,
    TBATF_USEMDILIVEPREVIEW = 0x2
}

public enum THB : uint
{
    THB_BITMAP = 0x1,
    THB_ICON = 0x2,
    THB_TOOLTIP = 0x4,
    THB_FLAGS = 0x8
}

public enum THBF : uint
{
    THBF_ENABLED = 0,
    THBF_DISABLED = 0x1,
    THBF_DISMISSONCLICK = 0x2,
    THBF_NOBACKGROUND = 0x4,
    THBF_HIDDEN = 0x8
}

[StructLayout(LayoutKind.Sequential, Pack = 4, CharSet = CharSet.Auto)]
public struct THUMBBUTTON
{
    public THB dwMask;
    public uint iId;
    public uint iBitmap;
    public IntPtr hIcon;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = Windows.MAX_PATH)]
    public string szTip;
    public THBF dwFlags;
}

[ComImport]
[Guid("ea1afb91-9e28-4b86-90e9-9e9f8a5eefaf")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface ITaskbarList3
{
    // ITaskbarList
    void HrInit();
    void AddTab(IntPtr hwnd);
    void DeleteTab(IntPtr hwnd);
    void ActivateTab(IntPtr hwnd);
    void SetActiveAlt(IntPtr hwnd);

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

    // ITaskbarList3
    void SetProgressValue(IntPtr hwnd, ulong ullCompleted, ulong ullTotal);
    void SetProgressState(IntPtr hwnd, TBPF tbpFlags);
    void RegisterTab(IntPtr hwndTab, IntPtr hwndMDI);
    void UnregisterTab(IntPtr hwndTab);
    void SetTabOrder(IntPtr hwndTab, IntPtr hwndInsertBefore);
    void SetTabActive(IntPtr hwndTab, IntPtr hwndMDI, TBATF tbatFlags);

    void ThumbBarAddButtons(
        IntPtr hwnd,
        uint cButtons,
        [MarshalAs(UnmanagedType.LPArray)] THUMBBUTTON[] pButtons);

    void ThumbBarUpdateButtons(
        IntPtr hwnd,
        uint cButtons,
        [MarshalAs(UnmanagedType.LPArray)] THUMBBUTTON[] pButtons);

    void ThumbBarSetImageList(IntPtr hwnd, IntPtr himl);

    void SetOverlayIcon(
        IntPtr hwnd,
        IntPtr hIcon,
        [MarshalAs(UnmanagedType.LPWStr)] string pszDescription);

    void SetThumbnailTooltip(
        IntPtr hwnd,
        [MarshalAs(UnmanagedType.LPWStr)] string pszTip);

    void SetThumbnailClip(
        IntPtr hwnd,
        [MarshalAs(UnmanagedType.LPStruct)] Rectangle prcClip);
}