ListBox zerstört PaintEvent vom Menu

[EWeiss]

Delphi-Quellcode:

unit uListBox;

interface

uses Windows, Classes, Messages, uGlobal, uGDIUnit, uSkin, uDrawText,
  uCheckButton, uTrackBar, uFXEffect, Bass, uBass, uBassVis, BassVis;

type
  TListBox = class
  private
    FHListBox:  HWND;
    FHOwner  :  HWND;
    Img:        cardinal;
    LStyle:     DWORD;
    procedure  SubClass(WinHandle: HWND);
    procedure UnSubClass(WinHandle: HWND);
  public
    property Handle: HWND Read FHListBox;
    constructor Create(hOwner: HWND; FullpathImageName: string; x, y, xW, yH,
      PlayListID: integer; BackColor: COLORREF);
    destructor Destroy; override;
  end;

type
  LBTYPE = Record
    Forecolor : LongInt;
    Backcolor : LongInt;
    ForeColorSelected : LongInt;
    BackColorSelected : LongInt;
    BorderStyle : LongInt;
    DrawStyle : LongInt;
    ItemHeight : LongInt;
    hWnd : LongInt;
    Left : LongInt;
    Top  : LongInt;
    Width : LongInt;
    Height : LongInt;
    hFont : LongInt;
    Parent : LongInt;
  end;

var
  TMListBox : LBTYPE;

function ListBoxProc(WinHandle: HWND; Msg: UINT; wP: WParam; lP: LParam): LRESULT; stdcall;


implementation
var
  PrevWndProc, PrevWndProcLB: Integer;

constructor TListBox.Create(hOwner: HWND; FullpathImageName: string; x, y, xW, yH,
  PlayListID: integer; BackColor: COLORREF);
begin

  with SkinEngine do
  begin
      // Erstelle das  GDIPLUS image von Datei
      Img := AddResource(PAnsiChar(FullpathImageName));
      if Img <> 0 then
      begin
        // Hole die Thumb GDIPLUS image größe
        GetImageSize(Img, imgW, imgH);
        LStyle := {LBS_HASSTRINGS Or LBS_OWNERDRAWFIXED Or}
                  LBS_NOINTEGRALHEIGHT Or WS_CHILD {Or WS_VISIBLE}
                  Or WS_BORDER Or WS_VSCROLL;

        FHListBox := CreateWindowEx(WS_EX_CLIENTEDGE or WS_EX_TRANSPARENT,
          SKLISTBOX, nil, LStyle, x, y, xW, yH,
          hOwner, PlayListID, skInstance, nil);

        if FHListBox <> 0 then
        begin
          SetImageProperty(FHListBox, PROP_IMAGE_BACK, Img);
          TMListBox.DrawStyle := BackColor;
          TMListBox.hWnd := FHListBox;
          FHOwner := hOwner;
          SubClass(FHOwner);
        end else
          // Image löschen wenn Fehler
          DeleteResource(Img);
      end;
  end;
end;

destructor TListBox.Destroy;
begin
  UnSubClass(FHOwner);

  inherited Destroy;
end;

function WndProc(WinHandle: HWND; Msg: UINT; wP: WParam; lP: LParam): LRESULT; stdcall;
begin
  Case MSG of
     WM_CTLCOLORLISTBOX:
       Result := TMListBox.DrawStyle;
     WM_DRAWITEM:
         Result := 0
     Else
       Result := CallWindowProc(Pointer(PrevWndProc), WinHandle, Msg, wP, lP);
  end;

end;

procedure TListBox.SubClass(WinHandle: HWND);
begin
  PrevWndProc := SetWindowLong(WinHandle, GWL_WNDPROC, integer(@WndProc));
  PrevWndProcLB := SetWindowLong(TMListBox.hWnd, GWL_WNDPROC, integer(@ListBoxProc));

end;

procedure TListBox.UnSubClass(WinHandle: HWND);
begin
  SetWindowLong(WinHandle, GWL_WNDPROC, PrevWndProc);
  SetWindowLong(TMListBox.hWnd, GWL_WNDPROC, integer(@ListBoxProc));
end;

function ListBoxProc(WinHandle: HWND; Msg: UINT; wP: WParam; lP: LParam): LRESULT; stdcall;
begin
    Result := CallWindowProc(Pointer(PrevWndProcLB), WinHandle, Msg, wP, lP);

end;

end.

Was ist falsch das die ListBox das Zeichnen vom Menu zerstört ?

gruss Emil