thank you for your answer, now, i was making some test and i found what

*!* Its the label of my application, with this i found the window
lnHWD = FindWindow(0,' Modulo de Inventarios - Empacamos Calidad ' )

*!* with this, I try to find the window child, but i dont find it
lnHandleWindow = FindWindowEx (lnHWD,0,'prtProduccion.txt',0)

Do you know if some structure of windows of visual foxpro exists?

sorry for my english! ;)