Missing data points when plotting with Qt

[oss]

Hi everyone,

I just plotted about 50'000 data points using the Qt graphics toolkit and recognised that many data points are left out. I think the plot backend reduces the number of points due to performance reasons. However, if I change the graphics toolkit to gnuplot the result looks more like what I expect, i.e. much more points are plotted. On the other hand, if I do plot(x, y, '.') the result generated by Qt also looks fine. Is there a way to adjust the number of plotted points for the Qt toolkit when I do plot(x,y)?

Octave version is 4.2.1.