C＃文本编辑器，以另一种形式访问富文本框

Question

我正在用C＃开发文本编辑器，我有两个问题，

1）我想在richtextbox中选择文本时打开一个对话框（一个表格可以说是一个表格2）。 2）我想访问richtextbox中的所选文本（在main form1中）以对其执行格式化。

我无法执行这些任务，请尽快给予帮助。  代码如下：

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 Text_Editor {
 public partial class Form1: Form {

  public Form1() {
   InitializeComponent();
  }

  private void newToolStripMenuItem_Click(object sender, EventArgs e) {
   Form1 newForm = new Form1();
   newForm.Show();
  }

  private void openToolStripMenuItem_Click(object sender, EventArgs e) {
   int Count = 1;
   string Input_Name = "";
   FileOpen.Title = "Open a Text File"; // Change the title
   FileOpen.FileName = ""; // Blank space for the file name
   FileOpen.Filter = "Text Files|*.txt"; // Only files having txt extension
   FileOpen.Multiselect = true;

   // Check about Cancel
   if (FileOpen.ShowDialog() != DialogResult.Cancel) {
    Count = FileOpen.FileName.Count();
    if (Count > 1) {
     foreach(string item in FileOpen.FileNames) {
      Input_Name = item;
      Form1 newForm = new Form1();
      newForm.richTextBox1.LoadFile(Input_Name, RichTextBoxStreamType.PlainText);
      newForm.Text = item;
      newForm.Show();
     }
    } else {
     Input_Name = FileOpen.FileName;
     richTextBox1.LoadFile(Input_Name, RichTextBoxStreamType.PlainText);
    }
   } else {
    MessageBox.Show("No File Selected", "Message")
   }
  }
  private void saveToolStripMenuItem_Click(object sender, EventArgs e) {
   string Output_Name = "";
   FileOpen.Title = "Save a Text File"; // Change the title
   FileOpen.FileName = ""; // Blank space for the file name
   FileOpen.Filter = "Text Files|*.txt"; // Only files having txt extension
   if (FileOpen.ShowDialog() != DialogResult.Cancel) // Check Dialog Box
   {
    Output_Name = FileOpen.FileName;
    richTextBox1.SaveFile(Output_Name, RichTextBoxStreamType.PlainText);
   }
  }
  private void cutToolStripMenuItem_Click(object sender, EventArgs e) {
   if (richTextBox1.SelectedText != "") {
    richTextBox1.Cut();
   } else {
    MessageBox.Show("No text selected", "Message");
   }
  }
  private void copyToolStripMenuItem_Click(object sender, EventArgs e) {
   if (richTextBox1.SelectedText != "") {
    richTextBox1.Copy();
   } else {
    MessageBox.Show("No text selected", "Message");
   }
  }
  private void pasteToolStripMenuItem_Click(object sender, EventArgs e) {
   if (Clipboard.GetDataObject().GetDataPresent(DataFormats.Text)) {
    richTextBox1.Paste();
    Clipboard.Clear();
   } else {
    MessageBox.Show("No text to paste", "Message");
   }
  }
  private void richTextBox1_SelectionChanged(object sender, EventArgs e) {
   Style newStyle = new Style();
   newStyle.Show();
  }
 }
}
form2 Code
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 Text_Editor {
 public partial class Style: Form {
  public Style() {
   InitializeComponent();
  }
  private Form1 newDoc;
  private void fontDialog1_Apply(object sender, EventArgs e) {
   fontDialog1.ShowDialog();
  }
  private void button1_Click(object sender, EventArgs e) {
   Font new1, old;
   old = newDoc.richtextBox.selectdText;
   if (old.Bold) {
    new1 = new Font(old, old.Style & ~FontStyle.Bold);
   } else {
    new1 = new Font(old, old.Style | FontStyle.Bold);
   }
   newDoc.Text.SelectionFont = new1;
  }
 }
}