//HEADER- DATEI

class TColorPageControl : public TPageControl
{
__published:	// Von der IDE verwaltete Komponenten
private:	// Anwenderdeklarationen
  virtual void __fastcall ShowControl(Controls::TControl* AControl);

  TColor FPageColor;
  TColor FTabColor;
  TColor FTabSheetColor;
  TColor FTabSheetBorderColor;
  virtual void __fastcall CreateParams(Controls::TCreateParams &Params);
  virtual void __fastcall PaintWindow(HDC DC);
  virtual void __fastcall DrawTab(int TabIndex, const Windows::TRect &Rect, bool Active);

  void __fastcall SetPageColor(TColor C);
  void __fastcall SetTabColor(TColor C);
  void __fastcall SetTabSheetColor(TColor C);
  void __fastcall SetTabSheetBorderColor(TColor C);
public:		// Anwenderdeklarationen
        __fastcall TColorPageControl(TComponent* Owner);
__published:
  __property TColor PageColor ={read=FPageColor, write=SetPageColor};
  __property TColor TabColor ={read=FTabColor, write=SetTabColor};
  __property TColor TabSheetColor ={read=FTabSheetColor, write=SetTabSheetColor};
  __property TColor TabSheetBorderColor ={read=FTabSheetBorderColor, write=SetTabSheetBorderColor};
};
//---------------------------------------------------------------------------

//CPP- DATEI

void __fastcall TColorPageControl::ShowControl(Controls::TControl* AControl)
{
  TPageControl::ShowControl(AControl);
}
//---------------------------------------------------------------------------
void __fastcall TColorPageControl::SetPageColor(TColor C)
{
  FPageColor=C;
  Color=C;
  SetTabSheetBorderColor(C);
//  Invalidate();
}
//---------------------------------------------------------------------------
void __fastcall TColorPageControl::SetTabColor(TColor C)
{
  FTabColor=C;
  Invalidate();
}
//---------------------------------------------------------------------------
void __fastcall TColorPageControl::SetTabSheetColor(TColor C)
{
  FTabSheetColor=C;
  Brush->Color=C;
  Invalidate();
}
//---------------------------------------------------------------------------
void __fastcall TColorPageControl::SetTabSheetBorderColor(TColor C)
{
  FTabSheetBorderColor=C;
  Invalidate();
}
//---------------------------------------------------------------------------
__fastcall TColorPageControl::TColorPageControl(TComponent* Owner)
        : TPageControl(Owner)
{
  FPageColor=clBtnFace;
  FTabColor=clBtnFace;
  FTabSheetColor=clBtnFace;
  Color=FTabSheetColor;
  Brush->Color=FPageColor;
  Canvas->Brush->Color=FTabColor;
}
//---------------------------------------------------------------------------
void __fastcall TColorPageControl::CreateParams(Controls::TCreateParams &Params)
{
  HBRUSH BR;
  TCustomTabControl::CreateParams(Params);
/*
  BR=Params.WindowClass.hbrBackground;
  DeleteObject(BR);
  BR=GetStockObject(HOLLOW_BRUSH);
  Params.WindowClass.hbrBackground=BR;
*/
}
//---------------------------------------------------------------------------
void __fastcall TColorPageControl::PaintWindow(HDC DC)
{
  TRect R;
  R=DisplayRect;
  R.Left-=4;
  R.Top-=4;
  R.Right+=4;
  R.Bottom+=4;
  TCanvas *CV=new TCanvas;
  CV->Handle=DC;
  CV->Brush->Color=FTabSheetBorderColor;
  CV->FillRect(R);
  delete CV;
  if (OwnerDraw)
  {
    TPageControl::PaintWindow(DC);
  }
  else
  {
    TPageControl::PaintWindow(DC);
  }
}
//---------------------------------------------------------------------------
void __fastcall TColorPageControl::DrawTab(int TabIndex, const Windows::TRect &Rect, bool Active)
{
  //TPageControl::DrawTab(TabIndex,Rect,Active);
  Canvas->Brush->Color=FTabColor;
//  Canvas->FillRect(Rect);
  Canvas->TextRect(Rect,
                Rect.Left+(Rect.Width()-Canvas->TextWidth(Pages[TabIndex]->Caption)) / 2,
                Rect.Top+(Rect.Height()-Canvas->TextHeight(Pages[TabIndex]->Caption)) / 2,
                Pages[TabIndex]->Caption);
}

//---------------------------------------------------------------------------

void __fastcall TForm1::FormCreate(TObject *Sender)
{
  TTabSheet *TS;
  CPC=new TColorPageControl(this);
  CPC->Parent=this;
  TS=new TTabSheet(CPC);
  TS->PageControl=CPC;
  TS->Caption="T1";
  TS=new TTabSheet(CPC);
  TS->PageControl=CPC;
  TS->Caption="T2";
  TS=new TTabSheet(CPC);
  TS->PageControl=CPC;
  TS->Caption="T3";
  CPC->Left=50;
  CPC->Top=50;
  CPC->HotTrack=true;

  CPC->PageColor=clYellow;
  CPC->TabColor=clRed;
  CPC->TabSheetColor=clBlue;
  CPC->TabSheetBorderColor=clGreen;
  CPC->OwnerDraw=OD->Checked;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::FormDestroy(TObject *Sender)
{
  delete CPC;
}
//---------------------------------------------------------------------------

Vielleicht hilft das etwas.

void __fastcall TForm1::frm1_tabReiterDrawTab(TCustomTabControl *Control, int TabIndex, const TRect &ARect, bool Active)
{try {                                                                          // Fehlerroutine Start
 AnsiString z1; TColor f1,f2;                                                   // Vars definieren
 TTabSheet *PTab;                                                               // TabControl anlegen
 TCanvas *ACanvas;                                                              // Canvas vorbereiten
 TRect CRect;                                                                   // Rect vorbereiten

 CRect=ARect;                                                                   // Akt. Rect übergeben

 PTab   =frm1_tabReiter->Pages[TabIndex];                                       // Reiter als Control übergeben
 ACanvas=Control->Canvas;                                                       // Canvas übergeben
 z1     =PTab->Caption;                                                         // Text im Reiter

 f1=PrgFarbe;                                                                   // HG Farbe Standard
 f2=clBtnText;                                                                  // VG Farbe Standard

 if(Active==true) {                                                             // REITER IST AKTIV
  f1=clBtnHighlight; f2=clBlack;                                                // Voreinstellung
  switch(TabIndex) {                                                            // welcher Reiter?
  case 1: f1=clGreen;   f2=clWhite;       break;                                // PLAN
  case 2: f1=clMaroon;  f2=clWhite;       break;                                // SCHRANK
  case 3: f1=clNavy;    f2=clWhite;       break;                                // AUFTRÄGE
  case 4: f1=clYellow;  f2=clBlack;       break;                                // BEMERKUNG
  case 5: f1=clFuchsia; f2=clBlack;       break;                                // ZUSTÄNDIG
  case 6: f1=clOlive;   f2=clWhite;       break;                                // ZUBEHÖR
  case 7: f1=clGray;    f2=clWhite;       break;                                // HISTORIE
  case 8: f1=clRed;     f2=clWhite;       break;                                // DATEIEN
  }                                                                             // ende switch(TabIndex
 }                                                                              // ende if(Active

 ACanvas->Brush->Color=f1;                                                      // Farbe HG festlegen
 ACanvas->Font->Color =f2;                                                      // Farbe VG festlegen

 ACanvas->Font->Name="Arial"; ACanvas->Font->Size=8;                            // Schrift anpassen
 ACanvas->FillRect(CRect);                                                      // Fläche erst füllen
 DrawText(ACanvas->Handle,z1.c_str(),-1,&CRect,DT_CENTER | DT_VCENTER | DT_SINGLELINE); // Text schreiben

 } catch(Exception& e) { MessageBox(NULL, e.Message.c_str(), "TForm1::frm1_tabReiterDrawTab()", MB_OK); }  // Fehler anzeigen
}

Gruss Stefan