This sample code shows how to interate through all frames in order to test whether the 'copy' command is enabled:
procedure TForm1.Button1Click(Sender: TObject)
var
i: integer
begin
for i := 0 to (WebBrowser1.OleObject.Document.frames.Length - 1) do
if WebBrowser1.OleObject.Document.frames.item(i).document.queryCommandEnabled('Copy') then
ShowMessage('copy command is enabled for frame no.' + IntToStr(i));
end;