Option Explicit

Const EM_EMPTYUNDOBUFFER = 205
Const EM_CANUNDO = 198
Const EM_GETMODIFY = 184
Const EM_SETMODIFY = 185
Const EM_UNDO = 199

Const EM_CANPASTE = 1074
Const EM_FINDTEXT = 1080

Const EM_GETFIRSTVISIBLELINE = 206
Const EM_GETLINECOUNT = 186
Const EM_GETLINE = 196
Const EM_LINEFROMCHAR = 201
Const EM_LINEINDEX = 187

Const EM_EXLINEFROMCHAR = 1078 '(>64k text)
Const EM_LINESCROLL = 182
Const EM_SCROLLCARET = 183
Const EM_SETTABSTOPS = 203

Private Declare Function SendMessage Lib "user32" _
   Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As _
   Long, ByVal wParam As Long, lParam As Any) As _
   Long

Private Sub Command1_Click()
   ' make control undo edits
   SendMessage Text1.hwnd, EM_UNDO, 0, 0
End Sub

Private Sub Command2_Click()
   ' make the controls current text
   ' be its undo text
   SendMessage Text1.hwnd, EM_EMPTYUNDOBUFFER, 0, 0
End Sub

Private Sub Command3_Click()
   MsgBox IIf(Changed(Text1), "Yes!", "No.")
End Sub

Private Sub Command5_Click()
   ' mark text1 as changed
   SendMessage ctlTextBox.hwnd, EM_SETMODIFY, 1, 0
End Sub

Private Sub Form_Load()
   Show
End Sub

Public Function Changed(ByVal ctlTextBox As _ 
   TextBox)    As Boolean
   ' return state of edit flag
   Changed = _
      SendMessage(ctlTextBox.hwnd, EM_GETMODIFY, 0, _
      0) <> 0
End Function

Private Sub Command4_Click()
   MsgBox IIf(SendMessage(Text1.hwnd, EM_CANUNDO, 0, _ 
   0)        <> 0, "Yes!", "No.")
End Sub

Public Sub SaveData()
   Dim iTextBoxCount As Integer
   For iTextBoxCount = 0 To Controls.Count - 1
      If TypeOf Controls(iTextBoxCount) Is TextBox _
         Then
         If Changed(Controls(iTextBoxCount)) Then
            ' save data
         End If
      End If
   Next
End Sub