private void tsmiInnerbox_Click(object sender, EventArgs e)
{
FrmInnerboxOld frm = FrmInnerboxOld.GetSingleton();
frm.MdiParent = this;
frm.Show();
frm.Activate();
}
/// <summary>
/// 单例模式，返回单个窗体对象
/// </summary>
/// <returns></returns>
public static FrmInnerboxOld GetSingleton()
{
//if(frm==null || frm.IsDisposed)
if (frm == null)
{
frm = new FrmInnerboxOld();
}
return(frm);
}