SetForegroundWindow

C# Signature:

/// <summary>
    ///     Brings the thread that created the specified window into the foreground and activates the window. Keyboard input is
    ///     directed to the window, and various visual cues are changed for the user. The system assigns a slightly higher
    ///     priority to the thread that created the foreground window than it does to other threads.
    ///     <para>See for https://msdn.microsoft.com/en-us/library/windows/desktop/ms633539%28v=vs.85%29.aspx more information.</para>
    /// </summary>
    /// <param name="hWnd">
    ///     C++ ( hWnd [in]. Type: HWND )<br />A handle to the window that should be activated and brought to the foreground.
    /// </param>
    /// <returns>
    ///     <c>true</c> or nonzero if the window was brought to the foreground, <c>false</c> or zero If the window was not
    ///     brought to the foreground.
    /// </returns>
    /// <remarks>
    ///     The system restricts which processes can set the foreground window. A process can set the foreground window only if
    ///     one of the following conditions is true:
    ///     <list type="bullet">
    ///     <listheader>
    ///         <term>Conditions</term><description></description>
    ///     </listheader>
    ///     <item>The process is the foreground process.</item>
    ///     <item>The process was started by the foreground process.</item>
    ///     <item>The process received the last input event.</item>
    ///     <item>There is no foreground process.</item>
    ///     <item>The process is being debugged.</item>
    ///     <item>The foreground process is not a Modern Application or the Start Screen.</item>
    ///     <item>The foreground is not locked (see LockSetForegroundWindow).</item>
    ///     <item>The foreground lock time-out has expired (see SPI_GETFOREGROUNDLOCKTIMEOUT in SystemParametersInfo).</item>
    ///     <item>No menus are active.</item>
    ///     </list>
    ///     <para>
    ///     An application cannot force a window to the foreground while the user is working with another window.
    ///     Instead, Windows flashes the taskbar button of the window to notify the user.
    ///     </para>
    ///     <para>
    ///     A process that can set the foreground window can enable another process to set the foreground window by
    ///     calling the AllowSetForegroundWindow function. The process specified by dwProcessId loses the ability to set
    ///     the foreground window the next time the user generates input, unless the input is directed at that process, or
    ///     the next time a process calls AllowSetForegroundWindow, unless that process is specified.
    ///     </para>
    ///     <para>
    ///     The foreground process can disable calls to SetForegroundWindow by calling the LockSetForegroundWindow
    ///     function.
    ///     </para>
    /// </remarks>
// For Windows Mobile, replace user32.dll with coredll.dll 
[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool SetForegroundWindow(IntPtr hWnd);

VB.NET Signature

<DllImport("user32.dll")> _
Private Shared Function SetForegroundWindow(ByVal hWnd As IntPtr) As <MarshalAs(UnmanagedType.Bool)> Boolean
End Function

VB 6 Signature:

Private Declare Function SetForegroundWindow Lib "user32" (ByVal hwnd As IntPtr) As Long

Tips & Tricks:

MyWrapper.ShowWindow(targetHWnd, 6); //Minimize (ShowWindowCommands.Minimize)
    MyWrapper.ShowWindow(targetHWnd, 9); //Restore (ShowWindowCommands.Restore)

Sample Code (C#):

public static void Main(string[] args)
{
    // test code here...
    CheckAutFocus(myProcess.MainWindowHandle);
    // more test code...
}

public static void CheckAutFocus(hWnd)
{
    if (GetForegroundWindow() != hWnd)
    {
        SetForegroundWindow(hWnd);
    }
}

Sample Code (C#):

public static bool BringWindowToTop(string windowName, bool wait)
        {
            int hWnd = FindWindow(windowName, wait);
            if (hWnd != 0)
            {
                return SetForegroundWindow((IntPtr)hWnd);
            }
            return false;
        }

        // THE FOLLOWING METHOD REFERENCES THE FindWindowAPI
        public static int FindWindow(string windowName, bool wait)
        {
            int hWnd = FindWindow(null, windowName);
            while (wait && hWnd == 0)
            {
                System.Threading.Thread.Sleep(500);
                hWnd = FindWindow(null, windowName);
            }

            return hWnd;
        }