Suggestion: Enable/Disable Back and Forward buttons based on available history

[birbilis]

quoting from
http://dn.embarcadero.com/article/27726

These buttons are currently disabled and we only want them enabled when appropriate. To do this we will use the TWebBrowser's OnCommandStateChange event. The code should look like this:

procedure TForm1.WebBrowser1CommandStateChange(Sender: TObject;
  Command: Integer; Enable: WordBool);
begin
  case Command of
    CSC_NAVIGATEBACK: btnBack.Enabled := Enable;
    CSC_NAVIGATEFORWARD: btnForward.Enabled := Enable;
  end;
end;