委托事件實作窗體間互操作

// frm1
public delegate void FilterCol();
public event FilterCol FilterColEvent;

// frm1上又有一個Button
private void button1_Click(object sender, EventArgs e)
{
    FilterColEvent?.Invoke();//引發事件

    Close();
}      

if(FilterColEvent != null)
  FilterColEvent();      

// frm2
frm1 fm=new frm1();
fm.FilterColEvent += xxx;

void xxx()
{
    xxxxxxxxxx;
}