我在做一个软件时，FORM1的panel会放一个FORM2进去，怎样通过控制FORM2中的按钮来将FORM3放入FORM1的panel中

比如上面的第一个罪名，点击一下，这个panel放入下面的窗体

给你完整写了一个

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace Q1049803
{
    public partial class MainUI : Form
    {
        public MainUI()
        {
            InitializeComponent();
        }

        private void showWindow<T>(string name) where T : Form, new()
        {
            T frm;
            if (Application.OpenForms[name] != null)
            {
                frm = Application.OpenForms[name] as T;
            }
            else
            {
                frm = new T();
                frm.Name = name;
            }
            frm.TopLevel = false;
            frm.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
            frm.WindowState = FormWindowState.Maximized;
            frm.Parent = splitContainer1.Panel2;
            frm.Show();
            frm.BringToFront();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            showWindow<CaseRegister>("CaseRegister");
        }

        private void button2_Click(object sender, EventArgs e)
        {
            showWindow<CaseQuery>("CaseQuery");
        }

        private void button3_Click(object sender, EventArgs e)
        {
            if (Application.OpenForms["CaseRegister"] != null)
            {
                MessageBox.Show((Application.OpenForms["CaseRegister"] as CaseRegister).textBox1.Text);
            }
        }
    }
}

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