private void aboutToolStripMenuItem_Click(object sender, EventArgs e) { AboutDialog dlg = new AboutDialog(); foreach (Form fm in Application.OpenForms) { if (fm.Name == "AboutDialog") { return; } } dlg.Owner = this; dlg.StartPosition = FormStartPosition.Manual; dlg.SetDesktopLocation((this.DesktopLocation.X + this.Width), this.DesktopLocation.Y); dlg.Show(); }