property Edit.Overtype as Boolean
Specifies whether the control is running in overtype mode.

TypeDescription
Boolean A boolean expression that indicates whether the control is running the overtype/overstrike or insert mode.
By default, the Overtype property is False. The INSERT key toggles between overtype/overstrike and insert mode. overtype/overstrike replaces existing characters, insert adds new text where you start typing.

The following VB sample disables Overtype/Overstrike mode, when user presses Insert key:

Private Sub Edit1_KeyDown(KeyCode As Integer, Shift As Integer)
    If (KeyCode = vbKeyInsert) Then
        KeyCode = 0
    End If
End Sub