[jorodgar]

Solucion :

Código Delphi [-]
 
 procedure TForm1.Button2Click(Sender: TObject);
 var
   Start: Integer;
 begin
   RxRichEdit1.PlainText:=false;
   RxRichEdit1.SelAttributes.Color:=clRed;
   RxRichEdit1.Lines.add('hola esto es una prueba');
   RxRichEdit1.SelAttributes.Color:=clblue;
   RxRichEdit1.lines.add('para prueba www.clubdelphi.com');
   Start := RxRichEdit1.FindText('prueba', 0, Length(RxRichEdit1.Text), []);
 
   while start <> -1 do
   begin
 
     RxRichEdit1.SelStart := Start;
     RxRichEdit1.SelLength := Length('prueba');
     Clipboard.Assign(Image5.Picture);
     RxRichEdit1.PasteFromClipboard;
 //  RxRichEdit1.SelText := 'demo'
     Start := RxRichEdit1.FindText('prueba', 0, Length(RxRichEdit1.Text), []);
   end;
 end;