private void btn_Tear_Click(object sender, EventArgs e) { if (frmTear == null) { frmTear = new FormTear(); frmTear.Show(); //子窗口关闭后增加释放实例的功能 frmTear.FormClosing += ReleaseObjct_Tear; } else { //存在子窗口打开的时候,重新选择打开的子窗口 frmTear.Activate(); } }
private void ReleaseObjct_Tear(object sender, FormClosingEventArgs e) { //释放实例 frmTear = null; }