procedure TForm1.btn5Click(Sender: TObject);
 var
 i:integer;
 find_text:string;

begin

    find_text:=edt1.Text;
  // find_text:='слово';
   i:=Pos(find_text, redt1.Text)-1;


    while (i<=Length(redt1.Text)) do
    begin
     redt1.HideSelection:=False;
     redt1.SelStart:=PosEx(find_text, redt1.Text,i)-1;
     redt1.SelLength:=length(find_text);
     redt1.SelAttributes.Style := [fsItalic];
     Application.ProcessMessages;
     i:=i+length(find_text);
    end;


end;