ok i got It working
Declared at top
Dim WithEvents txt1 As TextBox
Cast the column to Textbox
Private Sub dgvInvoice_EditingControlShowing(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewEditingControlShowingEventArgs) Handles dgvInvoice.EditingControlShowing
Try
If dgvInvoice.CurrentCell.ColumnIndex = 3 Then
If TypeOf e.Control Is TextBox Then
txt1 = DirectCast(e.Control, TextBox)
End If
End If
Catch ex As Exception
MsgBox(ex.Message)
End Try
End Sub
and Finally Raised the textchanged Event
Public Sub txt1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txt1.TextChanged
If dgvInvoice.CurrentCell.ColumnIndex = 3 Then
--- DONE WHAT I WANTED
End If
End Sub