• https://foro.elhacker.net/net/autologin_en_otra_aplicacion_c-t489446.0.html;msg2178786#msg2178786

Friend NotInheritable Class NativeMethods
 
    Private Sub New()
    End Sub
 
    <DllImport("User32.dll", SetLastError:=True)>
    Friend Shared Function PostMessage(
        <MarshalAs(UnmanagedType.SysInt)> hWnd As IntPtr,
        <MarshalAs(UnmanagedType.U4)> msg As Integer,
        <MarshalAs(UnmanagedType.SysInt)> wParam As IntPtr,
        <MarshalAs(UnmanagedType.SysInt)> lParam As IntPtr
        ) As <MarshalAs(UnmanagedType.Bool)> Boolean
    End Function
 
End Class

Public Shared Function SendKeyDown(ByVal hWnd As IntPtr, ByVal key As Integer) As Boolean
    Const WM_KEYDOWN As Integer = 256
    Return NativeMethods.PostMessage(hWnd, WM_KEYDOWN, New IntPtr(key), IntPtr.Zero)
End Function
 
Public Shared Function SendKeyUp(ByVal hWnd As IntPtr, ByVal key As Integer) As Boolean
    Const WM_KEYUP As Integer = 257
    Return NativeMethods.PostMessage(hWnd, WM_KEYUP, New IntPtr(key), IntPtr.Zero)
End Function
 
Public Shared Function SendKeyPress(ByVal hWnd As IntPtr, ByVal key As Integer) As Boolean
    Return ((SendKeyDown(hWnd, key) And SendKeyUp(hWnd, key)) = True)
End Function

Dim hWnd As IntPtr = Process.GetProcessesByName("notepad").Single().MainWindowHandle
Dim key As Integer = System.Windows.Forms.Keys.F5 ' VK_F5 (0x74)
 
Dim success As Boolean = SendKeyPress(hWnd, key)
If Not (success) Then
    Dim win32ErrCode As Integer = Marshal.GetLastWin32Error()
    Throw New Win32Exception(win32ErrCode)
End If

Dim prDict As New SortedDictionary(Of String, Integer)(
    Process.GetProcesses().ToDictionary(Function(pr) String.Format("{0} [{1}]", pr.ProcessName, pr.Id),
                                        Function(pr) pr.Id), StringComparer.Ordinal)
 
Me.ListBox1.DataSource = prDict.Keys.ToList()

Private Sub ListBox1_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)
	Dim lb As ListBox = DirectCast(sender, ListBox)
	Dim pid As Integer = prDict(lb.SelectedItem.ToString())
	Dim pr As Process = Process.GetProcessById(pid)
	' ...
End Sub

SortedDictionary<string, int> prDict = 
    new SortedDictionary<string, int>(Process.GetProcesses().ToDictionary(
        (pr) => string.Format("{0} [{1}]", pr.ProcessName, pr.Id), (pr) => pr.Id), 
        StringComparer.Ordinal);
 
this.listBox1.DataSource = prDict.Keys.ToList();

private void listBox1_SelectedIndexChanged(object sender, EventArgs e) {
    ListBox lb = (ListBox)sender;
    int pid = prDict[lb.SelectedItem.ToString()];
    Process pr = Process.GetProcessById(pid);
    // ...
}

internal sealed class NativeMethods {
 
	private NativeMethods() {}
 
	[DllImport("User32.dll", SetLastError=true)]
	[return: MarshalAs(UnmanagedType.Bool)]
	internal extern static bool PostMessage([MarshalAs(UnmanagedType.SysInt)] IntPtr hWnd, 
	                                        [MarshalAs(UnmanagedType.U4)] uint msg, 
	                                        [MarshalAs(UnmanagedType.SysInt)] IntPtr wParam, 
	                                        [MarshalAs(UnmanagedType.SysInt)] IntPtr lParam);
 
}

[DllImport("user32.dll", EntryPoint="keybd_event", SetLastError=true)]
internal extern static void KeybdEvent([MarshalAs(UnmanagedType.U1)] byte vkey,
                                       [MarshalAs(UnmanagedType.U1)] byte scanCode, 
                                       [MarshalAs(UnmanagedType.U4)] KeybdEventFlags flags, 
                                       [MarshalAs(UnmanagedType.SysUInt)] UIntPtr extraInfo);
 
[DllImport("user32.dll", SetLastError=true)]
[return: MarshalAs(UnmanagedType.U4)]
internal extern static uint MapVirtualKey([MarshalAs(UnmanagedType.U4)] uint code, 
                                          [MarshalAs(UnmanagedType.U4)] MapVirtualKeyMapTypes mapType);

[Flags]
internal enum KeybdEventFlags: uint {
	NonExtendedKey = 0x0,
	ExtendedKey = 0x1,
	KeyUp = 0x2
}
 
internal enum MapVirtualKeyMapTypes: uint {
	VKeyToScanCode = 0x0,
	ScanCodeToVkey = 0x1,
	VKeyToChar = 0x2,
	ScanCodeToVKeyExtended = 0x3,
	VKeyToScanCodeExtended = 0x4
}

Dim hWnd As IntPtr = Process.GetProcessesByName("notepad").Single().MainWindowHandle
 
Dim modKey As Byte = CByte(Keys.LControlKey)
Dim scanCode As Byte = CByte(NativeMethods.MapVirtualKey(modKey, MapVirtualKeyMapTypes.VKeyToScanCode))
 
' Presionar modificador de tecla
NativeMethods.KeybdEvent(modKey, scanCode, KeybdEventFlags.NonExtendedKey, UIntPtr.Zero)
 
' Presionar la tecla "S"
SendKeyPress(hWnd, Keys.S)
Thread.Sleep(100) ' Intervalo necesario ya que PostMessage es asincrónico.
 
' Soltar modificador de tecla
NativeMethods.KeybdEvent(modKey, scanCode, KeybdEventFlags.NonExtendedKey Or KeybdEventFlags.KeyUp, UIntPtr.Zero)

PostMessage(proc.MainWindowHandle, WM_KEYDOWN, tecla1, 0);
PostMessage(proc.MainWindowHandle, WM_KEYDOWN, tecla2, 0);
PostMessage(proc.MainWindowHandle, WM_KEYUP, tecla2, 0);
PostMessage(proc.MainWindowHandle, WM_KEYUP, tecla1, 0);