Private Sub XDataGridView_CellMouseClick(sender As Object, e As _
  DataGridViewCellMouseEventArgs) Handles XDataGridView.CellMouseClick
 
  If e.Button = System.Windows.Forms.MouseButtons.Right Then
    If XDataGridView.Columns(e.ColumnIndex).HeaderText = "Proj. history" Then
      Form2.Show()
    End If
  End If
 
End Sub