C# 静态函数调用窗体控件

public partial class Form1 : Form
{
public static Form1 mainFrm;
public Form1()
{
mainFrm = this;
InitializeComponent();
}

public static void WaitCallBackReceiveConnectedInfo(string connecetedIp,string leaveIp)
{
Form1.mainFrm.rtxtMsg.BeginInvoke(new InvokeDelegate(InvokeMethod), new object[] { connecetedIp, leaveIp });

}
public delegate void InvokeDelegate(string connecetedIp, string leaveIp);
public static void InvokeMethod(string connecetedIp, string leaveIp)
{
if (connecetedIp != "")
{
Form1.mainFrm.cmbConnectedIP.Items.Add(connecetedIp);
Form1.mainFrm.rtxtMsg.AppendText(connecetedIp+" 连接上来\r\n");
Form1.mainFrm.cmbConnectedIP.SelectedIndex = 0;
}

if (leaveIp != "")
{
Form1.mainFrm.cmbConnectedIP.Items.Remove(leaveIp);
Form1.mainFrm.rtxtMsg.AppendText(leaveIp + " 离开\r\n");
}

}