private void tsAddPlugin_Click(object sender, EventArgs e)
        {
            OpenFileDialog dia = new OpenFileDialog();

            dia.Filter = @"Catalyst3D Plugins|*.dll";

            if (dia.ShowDialog() == DialogResult.OK)
            {
                // get the addins from that asm
                List <Addin> addins = AddinManager.ExamineAddin(dia.FileName);

                // install the addins
                AddinManager.LoadAddins(addins, AddinManager.Host);

                // refresh the grid with new addins
                rgPlugins.DataSource = null;
                rgPlugins.DataSource = AddinManager.Addins;
            }
        }