private static extern int SendMessage(IntPtr hWnd, WindowsMessages wMsg, IntPtr wParam, IntPtr lParam);

        //This version of SendMessage is a blocking call until all windows respond.

        long result = SendMessage(HWND_BROADCAST, WindowsMessages.WM_FONTCHANGE, IntPtr.Zero, IntPtr.Zero);

public SendMessage()

   SendMessage(hWnd, WM_COPYDATA, IntPtr.Zero, copyDataBuff);

Optionally call SendMessageTimeout() to notify running programs of the change:

    pinvokeResult = SendMessageTimeout(HWND_BROADCAST, WM_SETTINGCHANGE, IntPtr.Zero,

        IntPtr.Zero, SendMessageTimeoutFlags.SMTO_NORMAL, 1000, out innerPinvokeResult);

        pinvokeResult = SendMessageTimeout(HWND_BROADCAST, WM_SETTINGCHANGE, IntPtr.Zero,

            IntPtr.Zero, SendMessageTimeoutFlags.SMTO_NORMAL, 1000, out innerPinvokeResult);

$wtsSendMessagesig = @'

     public static extern bool WTSSendMessage(

$wtsmessage = Add-Type -MemberDefinition $wtsSendMessagesig -name PSWTSSendMessage -Namespace GetLoggedOnUsers -PassThru

     $wtsmessage::WTSSendMessage($server, $element.SessionID,$messageTitle,$messageTitle.Length,$message,$message.Length,0,$timeout,[ref]$resp,$true)

static extern bool WTSSendMessage(

  Private Shared Function WTSSendMessage(ByVal hServer As IntPtr, ByVal SessionId As Int32, ByVal title As String, ByVal titleLength As UInt32, ByVal message As String, ByVal messageLength As UInt32, ByVal style As UInt32, ByVal timeout As UInt32, ByRef pResponse As UInt32, ByVal bWait As Boolean) As Boolean

    public static extern bool WTSSendMessage(

$MessageBox = Add-Type memberDefinition $signature -name "WTSAPISendMessage" -namespace WTSAPI passThru

    result = WTSSendMessage(WTS_CURRENT_SERVER_HANDLE, WTS_CURRENT_SESSION, title, tlen, msg, mlen, 0, 0, out resp, false);

            public static extern bool WTSSendMessage(

                $MessageBox = Add-Type -memberDefinition $signature -name "WTSAPISendMessage" -namespace WTSAPI -passThru  

                $MessageBox::WTSSendMessage(0, $sessionId, $title, $titleLength, $message, $messageLength, $buttonSet, $timeout, [ref] $response, $waitResponse)

Sendmessage(hwndMain, WM_COMMAND, intMID,  0) 'Click the MenuItem!

        QS_SENDMESSAGE =    0x0040,

        QS_ALLINPUT = (QS_INPUT | QS_POSTMESSAGE | QS_TIMER | QS_PAINT | QS_HOTKEY | QS_SENDMESSAGE)

Sendmessage(hwndMain, WM_COMMAND, intMID,  0) 'Click the MenuItem!

To retrieve the text of a possibly unresponsive control in the same process, use SendMessageTimeout with a WM_GETTEXT message instead.

static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, [Out] StringBuilder lParam);

    int length = (int)SendMessage(hwnd, WM_GETTEXTLENGTH, IntPtr.Zero, IntPtr.Zero);

    SendMessage(hwnd, WM_GETTEXT, (IntPtr)sb.Capacity, sb);

static extern InSendMessageExFlags InSendMessageEx(IntPtr lpReserved);

InSendMessageExFlags

Win32.SendMessageTimeout(windowHandle, lMsg, IntPtr.Zero, IntPtr.Zero, SendMessageTimeoutFlags.SMTO_ABORT_IF_HUNG, 1000, out lRes);

    Private Shared Function SendMessage(ByVal hWnd As IntPtr,

        SendMessage(Handle, WM_NCLBUTTONDOWN, HT_CAPTION, 0)

private static extern int SendMessage(IntPtr hWnd, int msg , int wParam , ref int lParam);

   SendMessage(ctrl.Handle, WM_SYSCOMMAND, MOUSE_MOVE, ref nul);

  private static extern UInt32 SendMessage(

  lResult = SendMessage(  // returns LRESULT in lResult

    private static extern uint SendMessage(

    private static extern uint SendMessage(

        return (int)SendMessage(this._handle, SB_GETPARTS, 0, 0);

        uint length = (uint)SendMessage(this._handle, SB_GETTEXTLENGTH, index, 0);

            StatusBar.SendMessage(this._handle, SB_GETTEXT, (IntPtr)index, allocated);

  public static extern int SendMessage(int hWnd, uint Msg, int wParam, int lParam);

  public static extern int SendMessage(int hWnd, uint Msg, int wParam, int lParam);

      int lngResult = SendMessage(iHandle, WM_LBUTTONDOWN, 0, lparm);

      int lngResult2 = SendMessage(iHandle, WM_LBUTTONUP, 0, lparm);

  public static extern int SendMessage(int hWnd, uint Msg, int wParam, int lParam);

  public static extern int SendMessage(int hWnd, uint Msg, int wParam, int lParam);

      int lngResult = SendMessage(iHandle, WM_LBUTTONDOWN, 0, lparm);

      int lngResult2 = SendMessage(iHandle, WM_LBUTTONUP, 0, lparm);

public static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, uint wParam, StringBuilder lParam);

public static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, uint wParam, [MarshalAs(UnmanagedType.LPWStr)] string lParam);

public static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, uint wParam, [MarshalAs(UnmanagedType.LPWStr)] string lParam);

public static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, uint wParam, ref uint lParam);

public static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, uint wParam, uint lParam);

Public Shared Function SendMessage(ByVal hWnd As IntPtr, ByVal Msg As Integer, ByVal wParam As IntPtr, ByVal lParam As StringBuilder) As IntPtr

Public Shared Function SendMessage(ByVal hWnd As IntPtr, ByVal Msg As Integer, ByVal wParam As IntPtr, <MarshalAs(UnmanagedType.LPWStr)> ByVal lParam As String) As IntPtr

Public Shared Function SendMessage(ByVal hWnd As IntPtr, ByVal Msg As Integer, ByVal wParam As Integer, <MarshalAs(UnmanagedType.LPWStr)> ByVal lParam As String) As IntPtr

Public Shared Function SendMessage(ByVal hWnd As IntPtr, ByVal Msg As Integer, ByVal wParam As Integer, ByRef lParam As IntPtr) As IntPtr

Public Shared Function SendMessage(ByVal hWnd As IntPtr, ByVal Msg As Integer, ByVal wParam As Integer, ByVal lParam As IntPtr) As IntPtr

SendMessage(myCommandLink, BCM_SETNOTE, 0, "My CommandLink Note");

int length = SendMessage(myHwndHandle, WM_GETTEXTLENGTH, 0, 0).ToInt32();

SendMessage(myHwndHandle, WM_GETTEXT, length, builder);

    Dim length As Integer = SendMessage(hWnd, WM_GETTEXTLENGTH, 0, 0)

    SendMessage(hWnd, WM_GETTEXT, length+1, title)

private static extern int SendMessageA(int hWnd, int wMsg, int wParam, int lParam);

Declare Function SendMessageA Lib "user32.dll" (TODO) As TODO

static extern bool SendMessageCallback(IntPtr hWnd, uint Msg, UIntPtr wParam,

    IntPtr lParam, SendMessageDelegate lpCallBack, UIntPtr dwData);

C# signature for the SendMessageDelegate:

delegate void SendMessageDelegate(IntPtr hWnd, uint uMsg, UIntPtr dwData, IntPtr lResult);

public static extern IntPtr SendMessageTimeout(

    SendMessageTimeoutFlags fuFlags,

public static extern IntPtr SendMessageTimeout(

    SendMessageTimeoutFlags flags,

[DllImport("user32.dll", EntryPoint = "SendMessageTimeout", SetLastError=true, CharSet=CharSet.Auto)]

public static extern uint SendMessageTimeoutText(

    SendMessageTimeoutFlags flags,

SendMessageTimeoutFlags

Public Sub SendMessageTimeout(ByVal windowHandle As IntPtr,ByVal Msg As Integer,ByVal wParam As IntPtr,ByVal lParam As IntPtr,ByVal flags As SendMessageTimeoutFlags,ByVal timeout As Integer,ByRef result As IntPtr)

Public Shared Function SendMessageTimeout(ByVal windowHandle As IntPtr, ByVal Msg As Integer, ByVal wParam As IntPtr, ByVal lParam As IntPtr, ByVal flags As SendMessageTimeoutFlags, ByVal timeout As Integer, ByRef result As IntPtr) As IntPtr

Win32.SendMessageTimeout(windowHandle, lMsg, IntPtr.Zero, IntPtr.Zero, SendMessageTimeoutFlags.SMTO_ABORT_IF_HUNG, 1000, out lRes);

Public Declare Function SendNotifyMessage Lib "user32.dll" Alias "SendMessageA" ( _

    static extern int SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);

            SendMessage(hWndNextWindow, m.Msg, m.WParam, m.LParam);

            SendMessage(hWndNextWindow, m.Msg, m.WParam, m.LParam);

    static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, int wParam, int lParam);

    SendMessage(proc.MainWindowHandle, WM_SYSCOMMAND, SC_MAXIMIZE, 0);

    int res = SendMessage(handle, TCM_GETITEMA, index, tcitemPtr);

if ( SendMessageTimeout(hWnd, nMsg, UIntPtr.Zero, IntPtr.Zero,

     SendMessageTimeoutFlags.SMTO_ABORTIFHUNG, 1000, out lRes) == IntPtr.Zero )

There is a message (WM_SETTINGCHANGE) you can send in order to notify the active windows that there has been a configuration change using the SendMessageTimeout function.

        SendMessage(parent, WM_SIZE, SIZE_RESTORED, 0);

Use this method to get the list of items out of a combo box using Windows API call (SendMessage). You need to

get the count of items in the combo box first (also with SendMessage api).

        Dim ptrLength As Integer = SendMessage(windowHandle, ComboBox_GetComboBoxTextLength, iPtr, zero)

        SendMessage(windowHandle, ComboBox_GetComboBoxText, iPtr, winText)

Used in SendMessage API

        /// The caller is dispatching an intertask SendMessage call and cannot call out via PostMessage.

        public static extern IntPtr SendMessage(HandleRef hWnd, uint Msg, int wParam, IntPtr lParam);

        public static extern IntPtr SendMessage(HandleRef hWnd, int msg, int wParam, string lParam);

                //Win32.SendMessage(new HandleRef(null, hWnd), BFFM_SETSELECTIONA, 1, lpData);

                SendMessage(new HandleRef(null, hWnd), BFFM_SETSELECTIONW, 1, _initialPath);

                SendMessage(new HandleRef(null, hWnd), BFFM_SETSTATUSTEXTW, 0, pathPtr);

private static extern IntPtr SendMessage(IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);

Declare Function SendMessage Lib "coredll.dll" (ByVal hWnd As IntPtr, ByVal Msg As Integer, ByVal wParam As Integer, ByVal lParam As Integer) As IntPtr

    User32.SendMessage(listView1.Handle, User32.WM.WM_KEYDOWN, (int)User32.VK.VK_DOWN, 0);

    User32.SendMessage(listView1.Handle, User32.WM.WM_KEYUP, (int)User32.VK.VK_DOWN, 0);

    User32.SendMessage(listView1.Handle, User32.WM.WM_KEYDOWN, (int)User32.VK.VK_UP, 0);

    User32.SendMessage(listView1.Handle, User32.WM.WM_KEYUP, (int)User32.VK.VK_UP, 0);

    public static extern int SendMessage(IntPtr hWnd, WM Msg, int wParam, int lParam);

    User32.SendMessage(listView1.Handle, User32.WM.WM_KEYDOWN, (int)User32.VK.VK_UP, 0);

    User32.SendMessage(listView1.Handle, User32.WM.WM_KEYUP, (int)User32.VK.VK_UP, 0);

    public static extern int SendMessage(IntPtr hWnd, WM Msg, int wParam, int lParam);

    static extern int SendMessage(IntPtr hWnd, int wMsg, int wParam, int lParam);

        SendMessage(Handle, EM_LINESCROLL, 0, Row);

    ///The caller is dispatching an intertask SendMessage call and cannot call out via PostMessage.

    [Description("The caller is dispatching an intertask SendMessage call and cannot call out via PostMessage.")]

    '''The caller is dispatching an intertask SendMessage call and cannot call out via PostMessage.

    <Description("The caller is dispatching an intertask SendMessage call and cannot call out via PostMessage.")> _

[Flags] enum InSendMessageExFlags : uint

You can scroll a ListView using LVM_SCROLL with SendMessage. Example:

SendMessage(listView.Handle, (uint)ListViewMessages.LVM_SCROLL, scrollX, scrollY);

  PM_QS_SENDMESSAGE = QueueStatusFlags.QS_SENDMESSAGE << 16

    QS_SENDMESSAGE = 0x40,

    QS_ALLINPUT = (QS_SENDMESSAGE | QS_PAINT | QS_TIMER | QS_POSTMESSAGE | QS_MOUSEBUTTON | QS_MOUSEMOVE | QS_HOTKEY | QS_KEY),

    PM_QS_SENDMESSAGE = QueueStatusFlags.QS_SENDMESSAGE << 16

    QS_SENDMESSAGE = &H40

    QS_ALLINPUT = (QS_SENDMESSAGE Or QS_PAINT Or QS_TIMER Or QS_POSTMESSAGE Or QS_MOUSEBUTTON Or QS_MOUSEMOVE Or QS_HOTKEY Or QS_KEY)

  QS_SENDMESSAGE = 0x0040,

  QS_ALLINPUT = QS_INPUT | QS_POSTMESSAGE | QS_TIMER | QS_PAINT | QS_HOTKEY | QS_SENDMESSAGE

   QS_SENDMESSAGE = &H40

   QS_ALLINPUT = (QS_SENDMESSAGE Or QS_PAINT Or QS_TIMER Or QS_POSTMESSAGE Or QS_MOUSEBUTTON Or QS_MOUSEMOVE Or QS_HOTKEY Or QS_KEY)

enum SendMessageTimeoutFlags : uint

Public Enum SendMessageTimeoutFlags

    /// Sent by an application to direct the IME window to carry out the requested command. The application uses this message to control the IME window that it has created. To send this message, the application calls the SendMessage function with the following parameters.

    '''Sent by an application to direct the IME window to carry out the requested command. The application uses this message to control the IME window that it has created. To send this message the application calls the SendMessage function with the following parameters.

    ''' use the <see cref="NativeMethods.SendMessageTimeout"/> function with the <paramref name="hwnd"/> parameter set to