Problem solved with mooving to PyQtGraph. Thanks for help.
Vlado
import pyqtgraph as pg
OUT_Buffer_Time = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26] # 26 spominskih mest
OUT_Buffer_Zg = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0] # 26 spominskih mest
OUT_Buffer_Sp = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0] # 26 spominskih mest
def simple_graph():
H = pg.plot(OUT_Buffer_Time, OUT_Buffer_Zg, pen='b')
H.plot(OUT_Buffer_Time, OUT_Buffer_Zg, pen=(255, 0, 0))
H.plot(OUT_Buffer_Time, OUT_Buffer_Sp, pen=(0, 255, 200))