cla and clf can't work normally when plt.show is passed by false

[HikariS97]

plt::imshow(imageAddr, ptr->nRanges, ptr->nBeams, 1);
plt::show(false);
plt::clf();
plt::show(true);

Yes, plt::clf() works when the second plt::show() was set to true, but get invalid when set to false. This bug restricts me from fluent painting data msg. Can someone show me the right way to use plt::clf() or let me be noticed that this bug is reported. Because I have seen someone has the same trouble like me. #103