程式狂想曲

如果只是要消除  顯示的 三角形
 padding的參數中 設個數值就好
 datagridview1.RowHeadersDefaultCellStyle.Padding = New Padding(50)

 單純 設定 RowHeade 的文字

 以設定行號為例

For i As Integer = 0 To datagridview1.Rows.Count - 1
  datagridview1.Rows(i).HeaderCell.ValueType = GetType(String)
  datagridview1.Rows(i).HeaderCell.Value = i.ToString("00")
Next

如果要顯示 文字 又要消除三角形  需要修改 RowHead 的 Paint 事件

 datagridview1.RowHeadersDefaultCellStyle.Padding = New Padding(50)
  AddHandler datagridview1.RowPostPaint, AddressOf datagridview1_RowPostPaint

Private Sub datagridview1_RowPostPaint(ByVal sender As Object, ByVal e As DataGridViewRowPostPaintEventArgs)
        Dim o As Object = datagridview1.Rows(e.RowIndex).HeaderCell.Value

        If Not IsNothing(o) Then
            e.Graphics.DrawString(o.ToString(), datagridview1.Font, Brushes.Black, New PointF(e.RowBounds.Left + 2, (e.RowBounds.Top + 7)))
        End If

    End Sub