wxListBox Drag Reorder

#include <wx/wx.h>
#include <wx/listbox.h>

class TestBox : public wxListBox
{
private:
    wxColour* m_secondColor;
    bool m_isDragging;
    bool m_isPressing;
    bool m_hasScrolled;
    wxPoint m_lastPos;
    void paintLine(int y);
    void OnLeftDown(wxMouseEvent &event);
    void OnLeftUp(wxMouseEvent &event);
    void OnMove(wxMouseEvent &event);

public:
    TestBox(wxWindow* parent, wxWindowID id);
    void appendToList(wxString item, int pos);

    DECLARE_EVENT_TABLE()
};

BEGIN_EVENT_TABLE(TestBox, wxListBox)
  EVT_LEFT_DOWN         (TestBox::OnLeftDown)
  EVT_LEFT_UP           (TestBox::OnLeftUp)
  EVT_MOTION            (TestBox::OnMove)
END_EVENT_TABLE()

TestBox::TestBox(wxWindow* parent, wxWindowID id)
    : wxListBox(parent, id, wxDefaultPosition, wxDefaultSize, 0, NULL, wxLB_EXTENDED | wxBORDER_SIMPLE | wxLB_OWNERDRAW, wxDefaultValidator, wxListBoxNameStr)
{
    m_secondColor = new wxColour(235, 250, 255);
    m_isDragging = false;
    m_isPressing = false;
    m_hasScrolled = false;
    SetSize(610,430);
}

void TestBox::appendToList(wxString item, int pos)
{
    DeselectAll();

    int newPos = Insert(item, pos);
    SetSelection(newPos);

    int size = GetCount();
    bool foundPlaying = false;
    for (int i = 0; i < size; i++) {
        GetItem(i)->SetBackgroundColour((i % 2 == 0 ? *m_secondColor : *wxWHITE));
    }
}

void TestBox::paintLine(int y)
{
    wxClientDC dc(this);
    wxSize size = GetSize();
    int width = size.GetWidth();

    dc.SetPen(*wxGREY_PEN);
    dc.SetBrush(*wxGREY_BRUSH);
    dc.DrawLine(0, y, width, y);
}

void TestBox::OnLeftDown(wxMouseEvent &event)
{
    m_isPressing = true;
    if(!m_isDragging) {
        m_lastPos = event.GetPosition();
    }
    event.Skip();
}

void TestBox::OnLeftUp(wxMouseEvent &event)
{
    m_isPressing = false;

    if(m_isDragging) {
        m_isDragging = false;
        int scrollPos = GetScrollPos(wxVERTICAL);
        wxRect rect;
        wxArrayInt listIndex;
        static int itemHeight = -1;

         // If the itemHeight isn't set, set it here and now
        if (itemHeight == -1) {
            GetItemRect(0, rect);
            itemHeight = rect.height;
        }

        GetSelections(listIndex);
        if(listIndex.size() != 1) {
            m_hasScrolled = false;
            return;
        }

        int index = listIndex.Item(0);

        GetItemRect(index, rect);
        int currentY = rect.y;

        wxString item = GetString(index);
        this->Delete(index);

        if(m_hasScrolled) {
            index = scrollPos + ((event.GetY() + itemHeight/2) / itemHeight);
            m_hasScrolled = false;
        } else {
            index = HitTest(event.GetX(), (event.GetY() + itemHeight / 2) -1);
        }

        if (index > GetCount()) {
            index = GetCount();
        }

        int y = itemHeight * (index - scrollPos);
        if(y > currentY) {
            index--;
        }

        appendToList(item, index);
    }

    event.Skip();
}

void TestBox::OnMove(wxMouseEvent &event)
{
    if(!m_isPressing && !m_isDragging) {
        return;
    }

    if (event.m_controlDown || event.m_shiftDown) {
        m_isPressing = false;
        m_isDragging = false;
        Refresh();
        Update();
        return;
    }

    if (!m_isDragging) {
        static const int dragMinX = wxSystemSettings::GetMetric(wxSYS_DRAG_X);
        static const int dragMinY = wxSystemSettings::GetMetric(wxSYS_DRAG_Y);
        const wxPoint& pos = event.GetPosition();
        const wxPoint ofs = pos - m_lastPos;

        if ( abs(ofs.x) > dragMinX || abs(ofs.y) > dragMinY) {
            m_isDragging = true;
        }
    } else {
        static int lastY;
        static long lastTimestamp = 0;
        static int itemHeight = -1;

         // If the itemHeight isn't set, set it here and now
        if (itemHeight == -1) {
            wxRect rect;
            GetItemRect(0, rect);
            itemHeight = rect.height;
        }

        int y = event.GetY();
        int index = (y + itemHeight / 2) / itemHeight;

        if (index > GetCount())
            index = GetCount();

        y = itemHeight * index;

        // y > 25000 is a strange behaviour, happens when the cursor is outside the widget
        if (y <= 0 || y > 25000) {
            LineUp();
            m_hasScrolled = true;
        } else if (y >= GetSize().GetHeight()) {
            LineDown();
            m_hasScrolled = true;
        }

        if(event.GetTimestamp() - 60 > lastTimestamp && y != lastY) {
            Refresh();
            Update();
            paintLine(y);
            lastTimestamp = event.GetTimestamp();
        }
        lastY = y;
        return;
    }
    event.Skip();
}

class TestFrame : public wxFrame
{
public:
    TestFrame(const wxString& title)
       : wxFrame(NULL, wxID_ANY, title, wxDefaultPosition, wxSize(640, 480))
    {
        wxPanel* panel = new wxPanel(this, wxID_ANY);
        TestBox* list = new TestBox(panel, wxID_ANY);
        for(int i = 0; i < 500; i++) {
            list->appendToList(wxString::Format("%d - testtesttesttesttesttesttesttest", i), list->GetCount());
        }
        list->SetSelection(0);
        Centre();
    }
};

class TestApp : public wxApp
{
public:
    bool OnInit()
    {
        TestFrame* window = new TestFrame("Test");
        SetTopWindow(window);
        window->Centre();
        window->Show();
        return true;
    }
};

DECLARE_APP(TestApp);
IMPLEMENT_APP(TestApp);