Preference tab contents stretch weirdly for certain number of widgets

If I add a total of 10--15 widgets to e.g. BasePreferenceWindow.tabGrids[0], the 'startupgroup' stretches to fill the empty vertical space of the tab. Not coincidentally, the minimum vertical space of the preferences window on my pc appears to be 16 widgets, probably because that's the maximum number of widgets across all tabs.

This disappears if I set the 10 in grid.setRowStretch(10, 1) in BasePreferenceWindow.createTab to a number larger than the number of widgets.

I discovered this by accident. I am not (anymore) planning to add so many widgets, so it is not immediately relevant. Still, I guess we should call rowStretch (again) at the end of BasePreferenceWindow.build_settings_UI to the maximum number of widgets across tabs?.