Simple tool for using the FlashWindow() function.

FlashWindow.cs

[StructLayout(LayoutKind.Sequential)]
public struct FLASHWINFO
{
    public uint cbSize;
    public IntPtr hwnd;
    public uint dwFlags;
    public uint uCount;
    public uint dwTimeout;
}

[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
public static extern bool FlashWindowEx(ref FLASHWINFO pwfi);

// Flash window flags
public const uint FLASHW_STOP = 0;
public const uint FLASHW_CAPTION = 1;
public const uint FLASHW_TRAY = 2;
public const uint FLASHW_ALL = 3;
public const uint FLASHW_TIMER = 4;
public const uint FLASHW_TIMERNOFG = 12;

public static bool FlashWindowEx(IntPtr hWnd, uint flags, uint count, uint timeout)
{
    FLASHWINFO fInfo = new FLASHWINFO();
    fInfo.cbSize = Convert.ToUInt32(Marshal.SizeOf(fInfo));
    fInfo.hwnd = hWnd;
    fInfo.dwFlags = flags;
    fInfo.uCount = count;
    fInfo.dwTimeout = timeout;
    
    return FlashWindowEx(ref fInfo);
}

// Usage:
// Flash both caption and taskbar button 5 times
FlashWindowEx(this.Handle, FLASHW_ALL, 5, 0);