wxWidgets: class wxDialog * cannot convert to class wxApp *

The problem is exactly what is in the title, my wxWidgets application is breaking down because the conversion from the dialog class to the app class isn't working. Any help?

Error meassage:

error C2440: 'initializing': cannot convert from 'MP *' to 'MPApp *'

error C2664: 'void wxAppBase::SetTopWindow(wxWindow *)': cannot convert argument 1 from 'MPApp *' to 'wxWindow *'

error C2039: 'Show': is not a member of 'MPApp'

MPApp.cpp:

#include "MPApp.h"
#include "MP.h"

IMPLEMENT_APP(MPApp)

bool MPApp::OnInit()
{
    MPApp* dialog = new MP((NULL));
    SetTopWindow(dialog);
    dialog->Show(true);
    return true;
}

int MPApp::OnExit()
{
    return 0;
}

MPApp.h:

#ifndef __MPApp_h__
#define __MPApp_h__

#ifdef __BORLANDC__
#pragma hdrstop
#endif

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

class MPApp : public wxApp
{
public:
    bool OnInit();
    int OnExit();
};

#endif

MP.h:

#ifndef __MP_h__
#define __MP_h__

#ifdef __BORLANDC__
#pragma hdrstop
#endif

#ifndef WX_PRECOMP
#include <wx/wx.h>
#include <wx/dialog.h>
#else
#include <wx/wxprec.h>
#endif

#include <list>


#include <wx/menu.h>
#include <wx/timer.h>
#include <wx/listctrl.h>
#include <wx/textctrl.h>
#include <wx/stattext.h>
#include <wx/checkbox.h>
#include <wx/mediactrl.h>
#include <wx/slider.h>
#include <wx/button.h>
#include <wx/bmpbuttn.h>
#include <wx/panel.h>
#include <wx/sizer.h>
#include <wx/toplevel.h>

#undef MPSTYLE
#define MPSTYLE wxWANTS_CHARS | wxALWAYS_SHOW_SB | wxCAPTION | wxRESIZE_BORDER | wxSYSTEM_MENU  | wxDIALOG_NO_PARENT | wxMINIMIZE_BOX | wxMAXIMIZE_BOX | wxCLOSE_BOX

class MP : public wxDialog
{
private:
    DECLARE_EVENT_TABLE();
public:
    //Constuctor
    MP(wxWindow* parent, wxWindowID id = 0, const wxString& title = wxT("Music"), const wxPoint& pos = wxDefaultPosition, const wxSize& size = wxDefaultSize, long style = MPSTYLE);
    virtual ~MP();
    //Player
    void PlayFileNow();
    // EVENTS
    // Command Events
    void AddToQueue(wxCommandEvent& event);
    void WxButton1Click(wxCommandEvent& event);
    void PlayButtonClick(wxCommandEvent& event);
    void NextButtonClick(wxCommandEvent& event);
    void PreviousButtonClick(wxCommandEvent& event);
    void StopButtonClick(wxCommandEvent& event);
    void RandomCheckboxClick(wxCommandEvent& event);
    void WxButton2Click(wxCommandEvent& event);
    void SavePlaylistClick(wxCommandEvent& event);
    void LoadPlaylistClick(wxCommandEvent& event);
    void AddButtonClick(wxCommandEvent& event);
    void PlaylistsButtonClick(wxCommandEvent& event);
    void FindButtonClick(wxCommandEvent& event);
    void FindTextEditEnter(wxCommandEvent& event);
    void FindNextButtonClick(wxCommandEvent& event);
    void FindPrevButtonClick(wxCommandEvent& event);
    //Media Events
    void WxMediaCtrl1MediaFinished(wxMediaEvent& event);
    void WxMediaCtrl1MediaPause(wxMediaEvent& event);
    void WxMediaCtrl1MediaPlay(wxMediaEvent& event);
    void WxMediaCtrl1MediaStop(wxMediaEvent& event);
    void WxMediaCtrl1MediaLoaded(wxMediaEvent& event);
    //Key Events
    void HotKeyNext(wxKeyEvent& event);
    void HotKeyStop(wxKeyEvent& event);
    void HotKeyPlay(wxKeyEvent& event);
    void HotKeyPrev(wxKeyEvent& event);
    //List Events
    void WxListCtrl1ColLeftClick(wxListEvent& event);
    void WxListCtrl1ColRightClick(wxListEvent& event);
    void WxListCtrl1RightClick(wxListEvent& event);
    void WxListCtrl1ItemActivated(wxListEvent& event);
    void WxListCtrl1KeyDown(wxListEvent& event);
    //UI Event
    void SavePlaylistUpdateUI0(wxUpdateUIEvent& event);
    //Scroll Events
    void WxSlider2Scroll(wxScrollEvent& event);
    void WxSlider1Scroll(wxScrollEvent& event);
    //Timer Event
    void WxTimer1Timer(wxTimerEvent& event);
    //File Event
    void MPDropFiles(wxDropFilesEvent& event);
    //Mouse Event
    void MPRightUP(wxMouseEvent& event);
private:
//GUI Control
    //Menu items
    wxMenu* PlaylistMenu;
    wxMenu* WxPopupMenu1;
    wxMenu* AddMenu;
    //Timer item
    wxTimer* WxTimer1;
    //List item
    wxListCtrl* WxListCtrl1;
    //Button items
    wxButton* FindPrevButton;
    wxButton* FindNextButton;
    wxButton* AddButton;
    wxButton* PlaylistsButton;
    wxButton* FindButton;
        //Bitmaps
    wxBitmapButton* PlayButton;
    wxBitmapButton* PreviousButton;
    wxBitmapButton* NextButton;
    //Text items
    wxTextCtrl* FindTextEdit;
    wxStaticText* WxStaticText1;
    //Slider items
    wxSlider* WxSlider2;
    wxSlider* WxSlider1;
    //Panel items
    wxPanel* SearchPanel;
    wxPanel* WxPanel1;
    wxPanel* WxPanel;
    //Check item
    wxCheckBox* RandomCheckbox;
    //Media item
    wxMediaCtrl* WxMediaCtrl1;
    //Sizer items
    wxFlexGridSizer* WxFlexGridSizer1;
    wxBoxSizer* WxBoxSizer1;
private:
    //Enum IDs for GUI
    enum
    {
        ////GUI Enum Control ID Start
        ID_MNU_LOADPLAYLIST_1028 = 1028,
        ID_MNU_SAVEPLAYLIST_1029 = 1029,

        ID_MNU_PLAY_PAUSE_1019 = 1019,
        ID_MNU_STOP_1020 = 1020,
        ID_MNU_NEXT_1021 = 1021,
        ID_MNU_PREVIOUS_1022 = 1022,
        ID_MNU_ADDFOLDER_1023 = 1023,
        ID_MNU_SAVEPLAYLIST_1024 = 1024,
        ID_MNU_LOADPLAYLIST_1025 = 1025,

        ID_MNU_ADDFILES_1026 = 1026,
        ID_MNU_ADDFOLDER_1027 = 1027,

        ID_WXTIMER1 = 1017,
        ID_WXLISTCTRL1 = 1015,
        ID_FINDPREVBUTTON = 1034,
        ID_FINDNEXTBUTTON = 1033,
        ID_FINDEDITTXT = 1044,
        ID_WXSTATICTEXT1 = 1032,
        ID_SEARCHPANEL = 1031,
        ID_FINDBUTTON = 1030,
        ID_RANDOMCHECKBOX = 1018,
        ID_WXMEDIACTRL1 = 1016,
        ID_WXSLIDER2 = 1014,
        ID_WXSLIDER1 = 1013,
        ID_ADDBUTTON = 1008,
        ID_PLAYLISTS = 1007,
        ID_NEXTBUTTON = 1006,
        ID_STOPBUTTON = 1005,
        ID_PLAYBUTTON = 1004,
        ID_PREVIOUSBUTTON = 1003,
        ID_WXPANEL2 = 1002,
        ID_WXPANEL1 = 1011,
        ////GUI Enum Control ID End
        ID_HOT_PLAY,
        ID_HOT_STOP,
        ID_HOT_NEXT,
        ID_HOT_PREV,
        ID_DUMMY_VALUE_ //don't remove this value unless you have other enum values
    };

private:
    void OnClose(wxCloseEvent& event);
    void CreateGUIControls();
protected:
    // No description
    void AddFilesFromFolder(wxString FileName);
    //FileList Dirs, Files;
    //wxTreeItemId root;
    bool isPlaying;
    long selItem;
    // No description
    void PlayThisFile(long id);
    // No description
    void PlayFromQueue();
    std::list<wxString> lastPlayed, nextPlay;
    // No description
    void PlayNextFile();
    void DeselectAllFiles();

};

#endif

I couldn't include MP.cpp due to the length of the file, but it compiles fine and I have already debugged the issues.