Особенность XE8

uses VCL.Themes
var LDetails: TThemedElementDetails; LColor: TColor; 
begin
LDetails := StyleServices.GetElementDetails(tlGroupHeaderOpen); // вот этих констант целая куча
StyleServices.GetElementColor(LDetails,ecHeading1TextColor,LColor); 
GroupBox1.Font.Color := LColor; end;

      type
  TGroupBox = class(Vcl.StdCtrls.TGroupBox) // перед классом формы
  private
    FCaptionFont: TFont;
    procedure SetCaptionFont(AFont: TFont);
 
  public
    constructor Create(AOwner: TComponent); override;
    procedure Paint; override;
 
  published
    property CaptionFont: TFont read FCaptionFont write SetCaptionFont;
  end;
 
  TForm1 = class(TForm) // дальше все без изменений
 
// ...
 
 
// –еализаци¤
 
{ TGroupBox }
constructor TGroupBox.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  FCaptionFont := Font;
end;
 
procedure TGroupBox.Paint;
var
  Height: Integer;
  R: TRect;
  Flags: Cardinal;
  CRect, ORect: TRect;
  Size: TSize;
  tbBox: TThemedButton;
  teDetails: TThemedElementDetails;
 
begin
  with Canvas do
  begin
    Font := FCaptionFont;
    if StyleServices.Enabled then
    begin
      if Text <> '' then
      begin
        GetTextExtentPoint32(Handle, PChar(Text), length(Text), Size);
        CRect := Rect(0, 0, Size.cx, Size.cy);
        if not UseRightToLeftAlignment then
          OffsetRect(CRect, 8, 0)
        else
          OffsetRect(CRect, Width - 8 - CRect.Right, 0);
      end
      else
        CRect := Rect(0, 0, 0, 0);
      ORect := ClientRect;
      ORect.Top := (CRect.Bottom - CRect.Top) div 2;
      with CRect do
        ExcludeClipRect(Handle, Left, Top, Right, Bottom);
      if Enabled then
        tbBox := tbGroupBoxNormal
      else
        tbBox := tbGroupBoxDisabled;
      teDetails := StyleServices.GetElementDetails(tbBox);
      StyleServices.DrawElement(Handle, teDetails, ORect);
 
      SelectClipRgn(Handle, 0);
      if Text <> '' then
        Brush.Color := Color;
      Font := FCaptionFont;
      DrawText(Handle, PChar(Text), length(Text), CRect, Flags);
    end
    else
    begin
      Height := TextHeight('0');
      R := Rect(0, Height div 2 - 1, Width, Height);
 
      if Ctl3D then
      begin
        inc(R.Left);
        inc(R.Top);
        Brush.Color := clBtnHighlight;
 
        FrameRect(R);
 
        OffsetRect(R, -1, -1);
        Brush.Color := clBtnShadow;
      end
      else
        Brush.Color := clWindowFrame;
      FrameRect(R);
 
      if Text <> '' then
      begin
        if not UseRightToLeftAlignment then
          R := Rect(8, 0, 0, Height)
        else
          R := Rect(R.Right - Canvas.TextWidth(Text) - 8, 0, 0, Height);
        Flags := DrawTextBiDiModeFlags(DT_SINGLELINE);
        if Assigned(CaptionFont) then
          Font := CaptionFont;
        DrawText(Handle, PChar(Text), length(Text), R, Flags or DT_CALCRECT);
        Brush.Color := Color;
        DrawText(Handle, PChar(Text), length(Text), R, Flags);
      end;
    end;
  end;
end;
 
procedure TGroupBox.SetCaptionFont(AFont: TFont);
begin
  FCaptionFont := AFont;
  Repaint;
end;

 StyleServices.GetElementColor(LDetails,ecHeading1TextColor,LColor);