I wrote these about two years ago while controlling some vendor's application directly from my VB app. There are two classes, just copy each into their own class module and save. One is for an EDIT control (TextBox for us VBers), the other is for a ComboBox.
The Edit class:
Option Explicit
Private ghWnd As Long
Private gdlgID As Long
Public Property Get hwnd() As Long
hwnd = ghWnd
End Property
Public Property Let hwnd(ByVal hwnd As Long)
ghWnd = hwnd
End Property
Public Property Get dlgID() As Long
dlgID = gdlgID
End Property
Public Property Let dlgID(ByVal dlgID As Long)
gdlgID = dlgID
End Property
Public Function GetText(ByRef EditText As String, Optional ByVal dlgID As Long, Optional ByVal hwnd As Long) As Long
Dim hItem As Long
Dim ret As Long
Dim sMsg As String
GetText = -1
If hwnd = 0 Then hwnd = ghWnd
If hwnd = 0 Then
If IsMissing(dlgID) = True Then Exit Function 'no way to get hWnd if no dlgID
hwnd = GetDlgItem(ghWnd, dlgID)
End If
If hwnd = 0 Then Exit Function 'still 0, unable to continue
sMsg = Space(255)
GetText = SendMessageSTR(hwnd, WM_GETTEXT, Len(sMsg), sMsg)
EditText = StripNulls(sMsg)
End Function
Public Function SetText(ByVal TextToSet As String, Optional ByVal dlgID As Long, Optional ByVal hwnd As Long) As Long
Dim hItem As Long, ret As Long
If IsMissing(hwnd) = True Then hwnd = ghWnd 'no edit handle provided, use module copy
If hwnd <> 0 Then ghWnd = hwnd 'if hWnd is now nonzero, save to module var
If IsMissing(dlgID) = True Then dlgID = gdlgID 'if no control ID passed, use module copy
If dlgID <> 0 Then gdlgID = dlgID 'if control ID is now nonzero, save to module var
If ghWnd = 0 Then Exit Function 'still no valid handle
SetText = SendMessageSTR(ghWnd, WM_SETTEXT, Len(TextToSet), TextToSet)
End Function
The Combo class:
Option Explicit
Private ghWnd As Long
Private gdlgID As Long
Public Property Get hwnd() As Long
hwnd = ghWnd
End Property
Public Property Let hwnd(ByVal hwnd As Long)
ghWnd = hwnd
End Property
Public Property Get dlgID() As Long
dlgID = gdlgID
End Property
Public Property Let dlgID(ByVal dlgID As Long)
gdlgID = dlgID
End Property
Public Function AddString(ByVal NewString As String, Optional ByVal dlgID As Long, Optional ByVal hwnd As Long) As Long
Dim ret As Long
AddString = CB_ERR
If hwnd = 0 Then hwnd = ghWnd
If hwnd = 0 Then
If IsMissing(dlgID) = True Then Exit Function 'no way to get hWnd if no dlgID
hwnd = GetDlgItem(ghWnd, dlgID)
End If
If hwnd = 0 Then Exit Function 'still 0, unable to continue
AddString = SendMessageSTR(hwnd, CB_ADDSTRING, 0, NewString)
End Function
Public Function FindString(ByRef SearchString As String, Optional ByVal dlgID As Long, Optional ByVal hwnd As Long) As Long
Dim ret As Long
FindString = CB_ERR
If hwnd = 0 Then hwnd = ghWnd
If hwnd = 0 Then
If IsMissing(dlgID) = True Then Exit Function 'no way to get hWnd if no dlgID
hwnd = GetDlgItem(ghWnd, dlgID)
End If
If hwnd = 0 Then Exit Function 'still 0, unable to continue
FindString = SendMessageSTR(hwnd, CB_FINDSTRING, -1, SearchString)
End Function
Public Function SelectString(ByVal SearchString As String, Optional ByVal dlgID As Long, Optional ByVal hwnd As Long) As Long
Dim ret As Long
SelectString = CB_ERR
If hwnd = 0 Then hwnd = ghWnd
If hwnd = 0 Then
If IsMissing(dlgID) = True Then Exit Function 'no way to get hWnd if no dlgID
hwnd = GetDlgItem(ghWnd, dlgID)
End If
If hwnd = 0 Then Exit Function 'still 0, unable to continue
SelectString = SendMessageSTR(hwnd, CB_SELECTSTRING, -1, SearchString)
End Function
'CB_SELECTSTRING
'An application sends a CB_SELECTSTRING message to search the list of a combo box for an item that begins with the characters in a specified string. If a matching item is found, it is selected and copied to the edit control.
'
'To send this message, call the SendMessage function with the following parameters.
'
'SendMessage(
' (HWND) hWnd, // handle to destination window
' CB_SELECTSTRING, // message to send
' (WPARAM) wParam, // item of item preceding start
' (LPARAM) lParam // search string
');
'Parameters
'wParam
'Specifies the zero-based index of the item preceding the first item to be searched. When the search reaches the bottom of the list, it continues from the top of the list back to the item specified by the wParam parameter. If wParam is –1, the entire list is searched from the beginning.
'lParam
'Pointer to the null-terminated string that contains the characters for which to search. The search is not case sensitive, so this string can contain any combination of uppercase and lowercase letters.
'Return Values
'If the string is found, the return value is the index of the selected item. If the search is unsuccessful, the return value is CB_ERR and the current selection is not changed.
'
Oh you'll need these:
Public Declare Function GetDlgItem Lib "user32" (ByVal hDlg As Long, ByVal nIDDlgItem As Long) As Long
Public Declare Function SendMessageSTR Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal WMSG As Long, ByVal wParam As Long, ByVal lParam As String) As Long
Public Function StripNulls(ByVal string1 As String) As String
If Len(string1) > 0 Then
StripNulls = Split(string1, Chr(0))(0)
Else
StripNulls = ""
End If
End Function