Control expand in one instead of two directons

booksApp.cpp

#ifdef WX_PRECOMP
#include "wx_pch.h"
#endif

#ifdef __BORLANDC__
#pragma hdrstop
#endif //__BORLANDC__

#include "booksApp.h"
#include "booksMain.h"

IMPLEMENT_APP(booksApp);

bool booksApp::OnInit()
{
    booksMain* frame = new booksMain(_("Books MySQL"));
    frame->SetIcon(wxICON(appIcon)); // To Set App Icon
    frame->Show();
    return true;
}

booksApp.h

#pragma once

#include <wx/app.h>

class booksApp : public wxApp
{
public:
    virtual bool OnInit();
};

booksMain.cpp

#ifdef WX_PRECOMP
#include "wx_pch.h"
#endif

#ifdef __BORLANDC__
#pragma hdrstop
#endif //__BORLANDC__

#include "booksMain.h"

//helper functions
enum wxbuildinfoformat {
    short_f, long_f };

wxString wxbuildinfo(wxbuildinfoformat format)
{
    wxString wxbuild(wxVERSION_STRING);

    if (format == long_f )
    {
#if defined(__WXMSW__)
        wxbuild << _T("-Windows");
#elif defined(__WXMAC__)
        wxbuild << _T("-Mac");
#elif defined(__UNIX__)
        wxbuild << _T("-Linux");
#endif

#if wxUSE_UNICODE
        wxbuild << _T("-Unicode build");
#else
        wxbuild << _T("-ANSI build");
#endif // wxUSE_UNICODE
    }

    return wxbuild;
}

BEGIN_EVENT_TABLE(booksMain, wxFrame)
    EVT_CLOSE(booksMain::OnClose)
    EVT_BUTTON(idBtnQuit, booksMain::OnQuit)
    EVT_BUTTON(idBtnAbout, booksMain::OnAbout)
END_EVENT_TABLE()

booksMain::booksMain(const wxString &title)
    : wxFrame(NULL, wxID_ANY, title)
{
    this->SetSizeHints(wxDefaultSize, wxDefaultSize);
    wxBoxSizer* bSizer2;
    bSizer2 = new wxBoxSizer(wxHORIZONTAL);
    BtnAbout = new wxButton(this, idBtnAbout, wxT("&About"), wxDefaultPosition, wxDefaultSize, 0);
    bSizer2->Add(BtnAbout, 0, wxALL, 5);    
    BtnQuit = new wxButton(this, idBtnQuit, wxT("&Quit"), wxDefaultPosition, wxDefaultSize, 0);
    bSizer2->Add(BtnQuit, 0, wxALL, 5);
	ListView = new wxListView(this, idListView, wxDefaultPosition, wxSize(250, 200));
	ListView->AppendColumn("Column 1");
	ListView->InsertItem(0, "Item 1");
	ListView->InsertItem(1, "Item 2");
	ListView->InsertItem(2, "Item 3");
	bSizer2->Add(ListView, 0, wxEXPAND, 5);    
    this->SetSizer(bSizer2);
    this->Layout();
    bSizer2->Fit(this);
}


booksMain::~booksMain()
{
}

void booksMain::OnClose(wxCloseEvent &event)
{
    Destroy();
}

void booksMain::OnQuit(wxCommandEvent &event)
{
    Destroy();
}

void booksMain::OnAbout(wxCommandEvent &event)
{
    wxString msg = wxbuildinfo(long_f);
    wxMessageBox(msg, _("Welcome to..."));
}

booksMain.h

#pragma once

#ifndef WX_PRECOMP
    #include <wx/wx.h>
#endif

#include "booksApp.h"


#include <wx/button.h>
#include <wx/statline.h>
#include <wx/listctrl.h>

class booksMain: public wxFrame
{
private:
	void OnClose(wxCloseEvent& event);
	void OnQuit(wxCommandEvent& event);
	void OnAbout(wxCommandEvent& event);
	DECLARE_EVENT_TABLE()
protected:
    enum
    {
        idBtnQuit = 1000,
        idBtnAbout,
		idListView
    };
    wxButton* BtnAbout;
    wxButton* BtnQuit;
	wxListView *ListView;
public:
	booksMain(const wxString& title);
	~booksMain();
};