function checkBrowserIe()
  {
    var str = navigator.userAgent;
    if(str.search(/MSIE/i) != -1)
    {
      return true;
    }
    else
    {
      return false;
    }
  }

  function showLinkPrompt(form_name,input_name)
  {
    if(checkBrowserIe())
    {
      input_url = prompt("リンク先のアドレスを入力してください。","");
      if(input_url != null)
      {
        input_link_text = prompt("リンクの文章を入力してください","");
        if(input_link_text != null)
        {
          str = "＃リンク＃" + input_url + "＃" + input_link_text + "＃";
          insertStringToTextArea(form_name,input_name,str);
        }
      }
    }
    else
    {
      input_url = prompt("リンク先のアドレスを入力してください。","");
      if(input_url != null)
      {
        var cursor_range = new Array();
        getCursorRange(cursor_range,form_name,input_name);
        if(cursor_range["start"] == cursor_range["end"])
        {
          input_link_text = prompt("リンクの文章を入力してください","");
          if(input_link_text != null)
          {
            str = "＃リンク＃" + input_url + "＃" + input_link_text + "＃";
            insertStringToTextArea(form_name,input_name,str,cursor_range["start"]);
          }
        }
        else
        {
          str = "＃リンク＃" + input_url + "＃";
          insertStringToTextArea(form_name,input_name,str,cursor_range["start"]);
          cursor_range["end"] += str.length;
          str = "＃";
          insertStringToTextArea(form_name,input_name,str,cursor_range["end"]);
        }
      }
    }
  }

  function showImagePrompt(form_name,input_name)
  {
    if(checkBrowserIe())
    {
      input_url = prompt("画像のアドレスを入力してください。","");
      if(input_url != null)
      {
        str = "＃画像＃" + input_url + "＃";
        insertStringToTextArea(form_name,input_name,str);
      }
    }
    else
    {
      var cursor_range = new Array();
      getCursorRange(cursor_range,form_name,input_name);
      if(cursor_range["start"] == cursor_range["end"])
      {
        input_url = prompt("画像のアドレスを入力してください。","");
        if(input_url != null)
        {
          str = "＃画像＃" + input_url + "＃";
          insertStringToTextArea(form_name,input_name,str,cursor_range["start"]);
        }
      }
      else
      {
        str = "＃画像＃";
        insertStringToTextArea(form_name,input_name,str,cursor_range["start"]);
        cursor_range["end"] += str.length;
        str = "＃";
        insertStringToTextArea(form_name,input_name.str,cursor_range["end"]);
      }
    }
  }

  function insertStringToTextArea(form_name,input_name,str,insert_point)
  {
    if(input_name=="body")
    {
      insertStringToBody(form_name,str,insert_point);
    }
    else if(input_name=="board_header_text")
    {
      insertStringToBoardHeaderText(form_name,str,insert_point);
    }
    else if(input_name=="board_footer_text")
    {
      insertStringToBoardFooterText(form_name,str,insert_point);
    }
  }

  function insertStringToBody(form_name,str,insert_point)
  {
    if(checkBrowserIe())
    {
      document.forms[form_name].body.value += str;
      document.forms[form_name].body.focus();
    }
    else
    {
      var length = document.forms[form_name].body.value.length;
      var before = document.forms[form_name].body.value.slice(0,insert_point);
      var after = document.forms[form_name].body.value.slice(insert_point,length);
      document.forms[form_name].body.value = before + str + after;
      document.forms[form_name].body.focus();
      insert_point += str.length;
      document.forms[form_name].body.selectionStart = insert_point;
      document.forms[form_name].body.selectionEnd = insert_point;
      document.forms[form_name].body.focus();
    }
  }

  function insertStringToBoardHeaderText(form_name,str,insert_point)
  {
    if(checkBrowserIe())
    {
      document.forms[0].board_header_text.value += str;
      document.forms[0].board_header_text.focus();
    }
    else
    {
      var length = document.forms[0].board_header_text.value.length;
      var before = document.forms[0].board_header_text.value.slice(0,insert_point);
      var after = document.forms[0].board_header_text.value.slice(insert_point,length);
      document.forms[0].board_header_text.value = before + str + after;
      document.forms[0].board_header_text.focus();
      insert_point += str.length;
      document.forms[0].board_header_text.selectionStart = insert_point;
      document.forms[0].board_header_text.selectionEnd = insert_point;
      document.forms[0].board_header_text.focus();
    }
  }

  function insertStringToBoardFooterText(form_name,str,insert_point)
  {
    if(checkBrowserIe())
    {
      document.forms[0].board_footer_text.value += str;
      document.forms[0].board_footer_text.focus();
    }
    else
    {
      var length = document.forms[0].board_footer_text.value.length;
      var before = document.forms[0].board_footer_text.value.slice(0,insert_point);
      var after = document.forms[0].board_footer_text.value.slice(insert_point,length);
      document.forms[0].board_footer_text.value = before + str + after;
      document.forms[0].board_footer_text.focus();
      insert_point += str.length;
      document.forms[0].board_footer_text.selectionStart = insert_point;
      document.forms[0].board_footer_text.selectionEnd = insert_point;
      document.forms[0].board_footer_text.focus();
    }
  }

  function getCursorRange(cursor_range,form_name,input_name)
  {
    if(input_name=="body")
    {
      cursor_range["start"] = document.forms[form_name].body.selectionStart;
      cursor_range["end"] = document.forms[form_name].body.selectionEnd;
    }
    else if(input_name="board_header_text")
    {
      cursor_range["start"] = document.forms[0].board_header_text.selectionStart;
      cursor_range["end"] = document.forms[0].board_header_text.selectionEnd;
    }
    else if(input_name="board_footer_text")
    {
      cursor_range["start"] = document.forms[0].board_footer_text.selectionStart;
      cursor_range["end"] = document.forms[0].board_footer_text.selectionEnd;
    }
  }