doesn't remember the proportion of plot panes

both among them(main and the 2 aux), and relative to output pain.
That is, I can't make it remeber the following proportions by saving the config to Default or a custom one:

Inspecting the configuration files, I see that it simply doesn't update the fields:

MainPaneProportion
PlotPaneProportion
AuxPlotsProportion

when I drag the respective dividers.

Fityk 1.3.1, Windows