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 Const EM_UNDO = &HC7

Private Sub Command1_Click()
SendMessage Text1.hwnd, EM_UNDO, 0, 0
End Sub