为什么只有文字是彩色的，而不是TListView的所有标题？

Question

抱歉，无法对how to turn off hottracking on Delphi ListView?发表评论，我开始提出新问题。

遵循上述链接的建议，但当我点击标题文本时，列表显示如下：

我在drawItem中设置了brush.color，并在每行中设置了drawSubItem：

Sender.Canvas.Brush.Color := mycolor

但如果我点击标题的文字，那么在标题区域中，只有文字部分有彩色背景。

代码:(运行环境：XE6，Win8.1）

TMyTaskListView = class(TListView)
protected
  procedure CreateWnd; override;
end;

procedure TMyTaskListView.CreateWnd;
begin
  inherited;
  SetWindowTheme(WindowHandle, nil, nil);
end;

var
ListView1: TMyTaskListView;

Form.createForm:

ListView1.Columns.Add.Caption := 'TaskNo';
ListView1.Columns.Add.Caption := 'Task1';
ListView1.Columns.Add.Caption := 'Task2';
ListView1.Columns.Add.Caption := 'Task3';
ListView1.Columns.Add.Caption := 'Task Status';
ListView1.Items.Count := 5;

procedure TForm1.ListView1Data(Sender: TObject; Item: TListItem);
begin
    Item.Caption := IntToStr(Item.Index);
    Item.SubItems.Add('done');
    Item.SubItems.Add('error'); 
    Item.SubItems.Add('error');
    Item.SubItems.Add('error');
end;

 procedure TForm1.ListView1CustomDrawItem(Sender: TCustomListView;
   Item: TListItem; State: TCustomDrawState; var DefaultDraw: Boolean);
 begin

   if lstTaskItemCurClickBackgroundIndex = Item.Index then
         Sender.Canvas.Brush.Color := $cc;
 end;

 procedure TForm1.ListView1CustomDrawSubItem(Sender: TCustomListView;
   Item: TListItem; SubItem: Integer; State: TCustomDrawState;
   var DefaultDraw: Boolean);
 begin
   if lstTaskItemCurClickBackgroundIndex = Item.Index then
         Sender.Canvas.Brush.Color := $cc;
 end;
procedure TForm1.ListView1Click(Sender: TObject);
var
  ARect: TRect;
  Idx: Integer;
  SubItemIndex: Integer;
  pt: TPoint;
  item : TLIstItem;
  hittestinfo: TLVHitTestInfo;
  Rect: TRect;
begin
  Idx := -1;
  pt:= ListView1.ScreenToClient( mouse.cursorpos );
  item := ListView1.GetItemAt( pt.x, pt.y );
  If assigned( item ) then
    Idx := item.Index
  else
  begin
    FillChar( hittestinfo, sizeof( hittestinfo ), 0 );
    hittestinfo.pt := pt;
    If -1 <>ListView1.perform( LVM_SUBITEMHITTEST, 0, lparam(@hittestinfo))
    Then
    Begin
      Idx := hittestinfo.iItem;
      SubItemIndex := hittestinfo.iSubItem;
    End
    Else
      if (ListView1.Items.Count > 0) then
        Idx := 0;
  end;

  if Idx >= 0 then
  begin
    Rect  := ListView1.Items[Idx].DisplayRect(drBounds);

    if lstTaskItemPrevClickBackgroudColorRect <> Rect then
    begin
      InvalidateRect(ListView1.Handle, lstTaskItemPrevClickBackgroudColorRect, True);
      InvalidateRect(ListView1.Handle, Rect, True);
    end;
    lstTaskItemPrevClickBackgroudColorRect := Rect;
    lstTaskItemCurClickBackgroundIndex := Idx;
  end;
end;