docs code isn't working...

[David Amsalem]

iv'e been working on the reference docs for the mql5 lang

and i encountered a problem with the source code provided by the docs can someone tell me if it's 

the code or it's me missing out on some installation in my end 

Link to the docs page:  https://www.mql5.com/en/docs/basis/types/typedef

here's the code:

//+------------------------------------------------------------------+
//|                                                Panel_Buttons.mq5 |
//|                        Copyright 2017, MetaQuotes Software Corp. |
//|                                             https://www.mql5.com |
//+------------------------------------------------------------------+
 
#property copyright "Copyright 2017, MetaQuotes Software Corp."
#property link      "https://www.mql5.com"
#property version   "1.00"
#property description "The panel with several CButton buttons"
#include <Controls\Dialog.mqh>
#include <Controls\Button.mqh>
//+------------------------------------------------------------------+
//| defines                                                          |
//+------------------------------------------------------------------+
//--- indents and gaps
#define INDENT_LEFT                         (11)      // indent from left (with allowance for border width)
#define INDENT_TOP                          (11)      // indent from top (with allowance for border width)
#define CONTROLS_GAP_X                      (5)       // gap by X coordinate
#define CONTROLS_GAP_Y                      (5)       // gap by Y coordinate
//--- for buttons
#define BUTTON_WIDTH                        (100)     // size by X coordinate
#define BUTTON_HEIGHT                       (20)      // size by Y coordinate
//--- for the indication area
#define EDIT_HEIGHT                         (20)      // size by Y coordinate
 
//--- create the custom function type
typedef int(*TAction)(string,int);
//+------------------------------------------------------------------+
//|  Open the file                                                  |
//+------------------------------------------------------------------+
int Open(string name,int id)
  {
   PrintFormat("%s function called (name=%s id=%d)",__FUNCTION__,name,id);
   return(1);
  }
//+------------------------------------------------------------------+
//|  Save the file                                                  |
//+------------------------------------------------------------------+
int Save(string name,int id)
  {
   PrintFormat("%s function called (name=%s id=%d)",__FUNCTION__,name,id);
   return(2);
  }
//+------------------------------------------------------------------+
//|  Close the file                                                  |
//+------------------------------------------------------------------+
int Close(string name,int id)
  {
   PrintFormat("%s function called (name=%s id=%d)",__FUNCTION__,name,id);
   return(3);
  }
//+------------------------------------------------------------------+
//| Create the button class with the events processing function      |
//+------------------------------------------------------------------+
class MyButton: public CButton
  {
private:
   TAction           m_action;                    // chart events handler
public:
                     MyButton(void){}
                    ~MyButton(void){}
   //--- constructor specifying the button text and the pointer to the events handling function
                     MyButton(string text,TAction act)
     {
      Text(text);
      m_action=act;
     }
   //--- set the custom function called from the OnEvent() events handler
   void              SetAction(TAction act){m_action=act;}
   //--- standard chart events handler
   virtual bool      OnEvent(const int id,const long &lparam,const double &dparam,const string &sparam) override
     {
      if(m_action!=NULL && lparam==Id())
        {
         //--- call the custom handler
         m_action(sparam,(int)lparam);
         return(true);
        }
      else
      //--- return the result of calling the handler from the CButton parent class
         return(CButton::OnEvent(id,lparam,dparam,sparam));
     }
  };
//+------------------------------------------------------------------+
//| CControlsDialog class                                            |
//| Objective: graphical panel for managing the application       |
//+------------------------------------------------------------------+
class CControlsDialog : public CAppDialog
  {
private:
   CArrayObj         m_buttons;                     // button array
public:
                     CControlsDialog(void){};
                    ~CControlsDialog(void){};
   //--- create
   virtual bool      Create(const long chart,const string name,const int subwin,const int x1,const int y1,const int x2,const int y2) override;
   //--- add the button
   bool              AddButton(MyButton &button){return(m_buttons.Add(GetPointer(button)));m_buttons.Sort();};
protected:
   //--- create the buttons 
   bool              CreateButtons(void);
  };
//+------------------------------------------------------------------+
//| Create the CControlsDialog object on the chart                   |
//+------------------------------------------------------------------+
bool CControlsDialog::Create(const long chart,const string name,const int subwin,const int x1,const int y1,const int x2,const int y2)
  {
   if(!CAppDialog::Create(chart,name,subwin,x1,y1,x2,y2))
      return(false);
   return(CreateButtons());
//---
  }
//+------------------------------------------------------------------+
//| Create and add buttons to the CControlsDialog panel           |
//+------------------------------------------------------------------+
bool CControlsDialog::CreateButtons(void)
  {
//--- calculate buttons coordinates
   int x1=INDENT_LEFT;
   int y1=INDENT_TOP+(EDIT_HEIGHT+CONTROLS_GAP_Y);
   int x2;
   int y2=y1+BUTTON_HEIGHT;
//--- add buttons objects together with pointers to functions
   AddButton(new MyButton("Open",Open));
   AddButton(new MyButton("Save",Save));
   AddButton(new MyButton("Close",Close));
//--- create the buttons graphically
   for(int i=0;i<m_buttons.Total();i++)
     {
      MyButton *b=(MyButton*)m_buttons.At(i);
      x1=INDENT_LEFT+i*(BUTTON_WIDTH+CONTROLS_GAP_X);
      x2=x1+BUTTON_WIDTH;
      if(!b.Create(m_chart_id,m_name+"bt"+b.Text(),m_subwin,x1,y1,x2,y2))
        {
         PrintFormat("Failed to create button %s %d",b.Text(),i);
         return(false);
        }
      //--- add each button to the CControlsDialog container
      if(!Add(b))
         return(false);
     }
//--- succeed
   return(true);
  }
//--- declare the object on the global level to automatically create it when launching the program
CControlsDialog MyDialog;
//+------------------------------------------------------------------+
//| Expert initialization function                                   |
//+------------------------------------------------------------------+
int OnInit()
  {
//--- now, create the object on the chart
   if(!MyDialog.Create(0,"Controls",0,40,40,380,344))
      return(INIT_FAILED);
//--- launch the application
   MyDialog.Run();
//--- application successfully initialized
   return(INIT_SUCCEEDED);
  }
//+------------------------------------------------------------------+
//| Expert deinitialization function                                 |
//+------------------------------------------------------------------+
void OnDeinit(const int reason)
  {
//--- destroy dialog
   MyDialog.Destroy(reason);
  }
//+------------------------------------------------------------------+
//| Expert chart event function                                      |
//+------------------------------------------------------------------+
void OnChartEvent(const int id,         // event ID  
                  const long& lparam,   // event parameter of the long type
                  const double& dparam, // event parameter of the double type
                  const string& sparam) // event parameter of the string type
  {
//--- call the handler from the parent class (here it is CAppDialog) for the chart events
   MyDialog.ChartEvent(id,lparam,dparam,sparam);
  }