Private Declare Function FindWindow Lib "user32.dll" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
Private Declare Function SetWindowText Lib "user32.dll" Alias "SetWindowTextA" (ByVal hwnd As Long, ByVal lpString As String) As Long

Private Sub Command1_Click()
    Dim Ret As Long
    Ret = FindWindow(vbNullString, Text1.Text)
    SetWindowText Ret, Text2.Text
End Sub

Private Declare Function CreateToolhelpSnapshot Lib "kernel32" Alias "CreateToolhelp32Snapshot" (ByVal lFlags As Long, ByVal lProcessID As Long) As Long

Private Declare Function ProcessFirst Lib "kernel32" Alias "Process32First" (ByVal hSnapShot As Long, uProcess As PROCESSENTRY32) As Long
Private Declare Function ProcessNext Lib "kernel32" Alias "Process32Next" (ByVal hSnapShot As Long, uProcess As PROCESSENTRY32) As Long
Private Declare Sub CloseHandle Lib "kernel32" (ByVal hPass As Long)

Private Type PROCESSENTRY32
dwSize As Long
cntUsage As Long
th32ProcessID As Long
th32DefaultHeapID As Long
th32ModuleID As Long
cntThreads As Long
th32ParentProcessID As Long
pcPriClassBase As Long
dwFlags As Long
szExeFile As String * 260
End Type

'Para llenar el listbox con los procesos
Sub RellenaLista()
On Error Resume Next
Dim hSnapShot As Long
Dim uProceso As PROCESSENTRY32
Dim res As Long
List1.Clear
hSnapShot = CreateToolhelpSnapshot(2&, 0&)
If hSnapShot <> 0 Then
uProceso.dwSize = Len(uProceso)
res = ProcessFirst(hSnapShot, uProceso)
Do While res
List1.AddItem Left$(uProceso.szExeFile, InStr(uProceso.szExeFile, Chr$(0)) - 1)
List1.ItemData(List1.NewIndex) = uProceso.th32ProcessID
res = ProcessNext(hSnapShot, uProceso)
Loop
Call CloseHandle(hSnapShot)
End If

End Sub

Private Sub Form_Load()
RellenaLista
End Sub