如果你正在使用vcl样式，你必须写一个vcl样式钩子来在选项卡控件中绘制一个关闭按钮，看看Vcl.Styles.ColorTabs单元（在这些文章Creating colorful tabsheets with the VCL Styles，Added border to TTabColorControlStyleHook中介绍），了解你需要写一个这样的样式钩子。除了在选项卡中绘制按钮的代码之外，您还必须处理WM_MOUSEMOVE和WM_LBUTTONUP消息（在样式钩子中）以更改按钮的状态（正常，热）并检测关闭按钮中的单击。
如果你在实现样式钩子时遇到问题，让我知道在这里发布完整的解决方案。

更新

我只是写了这个简单的样式钩子来为选项卡中的关闭按钮添加支持。

uses
  Vcl.Styles,
  Vcl.Themes;

type
  TTabControlStyleHookBtnClose = class(TTabControlStyleHook)
  private
    FHotIndex       : Integer;
    FWidthModified  : Boolean;
    procedure WMMouseMove(var Message: TMessage); message WM_MOUSEMOVE;
    procedure WMLButtonUp(var Message: TWMMouse); message WM_LBUTTONUP;
    function GetButtonCloseRect(Index: Integer):TRect;
  strict protected
    procedure DrawTab(Canvas: TCanvas; Index: Integer); override;
    procedure MouseEnter; override;
    procedure MouseLeave; override;
  public
    constructor Create(AControl: TWinControl); override;
  end;

constructor TTabControlStyleHookBtnClose.Create(AControl: TWinControl);
begin
  inherited;
  FHotIndex:=-1;
  FWidthModified:=False;
end;

procedure TTabControlStyleHookBtnClose.DrawTab(Canvas: TCanvas; Index: Integer);
var
  Details : TThemedElementDetails;
  ButtonR : TRect;
  FButtonState: TThemedWindow;
begin
  inherited;

  if (FHotIndex>=0) and (Index=FHotIndex) then
   FButtonState := twSmallCloseButtonHot
  else
  if Index = TabIndex then
   FButtonState := twSmallCloseButtonNormal
  else
   FButtonState := twSmallCloseButtonDisabled;

  Details := StyleServices.GetElementDetails(FButtonState);

  ButtonR:= GetButtonCloseRect(Index);
  if ButtonR.Bottom - ButtonR.Top > 0 then
   StyleServices.DrawElement(Canvas.Handle, Details, ButtonR);
end;

procedure TTabControlStyleHookBtnClose.WMLButtonUp(var Message: TWMMouse);
Var
  LPoint : TPoint;
  LIndex : Integer;
begin
  LPoint:=Message.Pos;
  for LIndex := 0 to TabCount-1 do
   if PtInRect(GetButtonCloseRect(LIndex), LPoint) then
   begin
      if Control is TPageControl then
      begin
        TPageControl(Control).Pages[LIndex].Parent:=nil;
        TPageControl(Control).Pages[LIndex].Free;
      end;
      break;
   end;
end;

procedure TTabControlStyleHookBtnClose.WMMouseMove(var Message: TMessage);
Var
  LPoint : TPoint;
  LIndex : Integer;
  LHotIndex : Integer;
begin
  inherited;
  LHotIndex:=-1;
  LPoint:=TWMMouseMove(Message).Pos;
  for LIndex := 0 to TabCount-1 do
   if PtInRect(GetButtonCloseRect(LIndex), LPoint) then
   begin
      LHotIndex:=LIndex;
      break;
   end;

   if (FHotIndex<>LHotIndex) then
   begin
     FHotIndex:=LHotIndex;
     Invalidate;
   end;
end;

function TTabControlStyleHookBtnClose.GetButtonCloseRect(Index: Integer): TRect;
var
  FButtonState: TThemedWindow;
  Details : TThemedElementDetails;
  R, ButtonR : TRect;
begin
  R := TabRect[Index];
  if R.Left < 0 then Exit;

  if TabPosition in [tpTop, tpBottom] then
  begin
    if Index = TabIndex then
      InflateRect(R, 0, 2);
  end
  else
  if Index = TabIndex then
    Dec(R.Left, 2)
  else
    Dec(R.Right, 2);

  Result := R;
  FButtonState := twSmallCloseButtonNormal;

  Details := StyleServices.GetElementDetails(FButtonState);
  if not StyleServices.GetElementContentRect(0, Details, Result, ButtonR) then
    ButtonR := Rect(0, 0, 0, 0);

  Result.Left :=Result.Right - (ButtonR.Width) - 5;
  Result.Width:=ButtonR.Width;
end;

procedure TTabControlStyleHookBtnClose.MouseEnter;
begin
  inherited;
  FHotIndex := -1;
end;

procedure TTabControlStyleHookBtnClose.MouseLeave;
begin
  inherited;
  if FHotIndex >= 0 then
  begin
    FHotIndex := -1;
    Invalidate;
  end;
end;

以这种方式注册

TStyleManager.Engine.RegisterStyleHook(TCustomTabControl, TTabControlStyleHookBtnClose);
  TStyleManager.Engine.RegisterStyleHook(TTabControl, TTabControlStyleHookBtnClose);

这是一个演示

我一直在做这个例子，我让它在 Delphi XE6的Metro UI上工作。
为了获得Tab名称和按钮之间的正确距离，我的解决方法是修改这一行

Result.Left := Result.Right - (ButtonR.Width);
//it was   Result.Left := Result.Right - (ButtonR.Width) -5;

并在PageController属性上设置更大的TabWith。
此外，提醒“注册”行，在单元结束前继续上课。

//...all the code of the unit

Initialization

TStyleManager.Engine.RegisterStyleHook(TCustomTabControl,
  TTabControlStyleHookBtnClose);
TStyleManager.Engine.RegisterStyleHook(TTabControl,
  TTabControlStyleHookBtnClose);

end.//final unit "end" =D