private void ToolColor_Click(object sender, EventArgs e) { //frmColor frm = new frmColor(); //frm.MdiParent = this; //OpenSubForm(frm); Form childForm = null; foreach (Form f in this.MdiChildren) { if (f is frmColor) { childForm = (frmColor)f; break; } else { f.WindowState = FormWindowState.Minimized; f.Show(); } } if (childForm != null) { childForm.Focus(); childForm.BringToFront(); childForm.WindowState = FormWindowState.Normal; } else { childForm = new frmColor(); childForm.MdiParent = this; OpenSubForm(childForm); } }