Desativar PopupMenu do TWebBrowser no Delphi
 
unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, OleCtrls, SHDocVw;



type
  TForm1 = class(TForm)
    WebBrowser1: TWebBrowser;
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    procedure AppMsg(var Msg: TMsg; var Handled: Boolean);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

function NomeClasse(const Janela: HWND): string;
var
  Buffer: array[0..250] of Char;
begin
  if GetClassName(Janela, Buffer, SizeOf(Buffer)) > 0 then
    Result := string(Buffer)
  else
    Result := '';
end;

procedure TForm1.AppMsg(var Msg: TMsg; var Handled: Boolean);
var
  P: TPoint;
  Janela: HWND;
begin
  case Msg.Message of
    WM_RBUTTONDOWN, WM_RBUTTONUP:
      if GetCursorPos(P) then
        Handled := NomeClasse(WindowFromPoint(P)) = 'Internet Explorer_Server';
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Application.OnMessage := AppMsg;
  WebBrowser1.Navigate('https://www.tecnobyte.com.br');
end;