Is it possible to change the font color of the TTabSheet tab Signature

Perhaps it can give you such inspiration. Again, note that this will only work on Windows and with themes disabled in your application.

uses
  ComCtrls, Windows, LCLType;

type
  TPageControl = class(ComCtrls.TPageControl)
  private
    procedure CNDrawItem(var Message: TWMDrawItem); message WM_DRAWITEM;
  protected
    procedure CreateParams(var Params: TCreateParams); override;
  end; 

implementation

procedure TPageControl.CreateParams(var Params: TCreateParams);
begin
  inherited CreateParams(Params);
  with Params do
  begin
    if not (csDesigning in ComponentState) then
      Style := Style or TCS_OWNERDRAWFIXED;
  end;
end;

procedure TPageControl.CNDrawItem(var Message: TWMDrawItem);
var
  FontHandle: HFONT;
  FontColor: COLORREF;
  FontObject: TLogFont;
  BrushColor: COLORREF;
  BrushHandle: HBRUSH;
begin
  with Message.DrawItemStruct^ do
  begin
    GetObject(Font.Handle, SizeOf(FontObject), @FontObject);
    case itemID of
      0:
      begin
        BrushColor := RGB(235, 24, 33);
        FontColor := clWhite;
        FontObject.lfWeight := FW_NORMAL;
        FontObject.lfItalic := 0;
      end;
      1:
      begin
        BrushColor := RGB(247, 200, 34);
        FontColor := clGreen;
        FontObject.lfWeight := FW_NORMAL;
        FontObject.lfItalic := 1;
      end;
      2:
      begin
        BrushColor := RGB(178, 229, 26);
        FontColor := clGreen;
        FontObject.lfWeight := FW_BOLD;
        FontObject.lfItalic := 1;
      end
      else
        BrushColor := ColorToRGB(clBtnFace);
    end;

    BrushHandle := CreateSolidBrush(BrushColor);
    FillRect(hDC, rcItem, BrushHandle);

    FontHandle := CreateFontIndirect(FontObject);
    try
      SelectObject(hDC, FontHandle);
      SetTextColor(hDC, FontColor);
      SetBkMode(hDC, TRANSPARENT);
      DrawTextEx(hDC, PChar(Page[itemID].Caption), -1, rcItem, DT_CENTER or
        DT_VCENTER or DT_SINGLELINE, nil);
    finally
      DeleteObject(FontHandle);
    end;
  end;
  Message.Result := 1;
end;

      

        
        
        
      

    

This is how it looks: