private void Form1_Load(object sender, EventArgs e) { FormListClusters formListClusters = new FormListClusters(); formListClusters.ShowInTaskbar = false; formListClusters.FormBorderStyle = FormBorderStyle.None; formListClusters.Dock = DockStyle.Fill; formListClusters.TopLevel = false; formListClusters.Visible = true; formListClusters.Text = ""; formListClusters.ControlBox = false; splitContainer.Panel1.Controls.Add(formListClusters); }