Letter size changeable?

Is there any way to change the letter size of the maintable and the group panels. On may display the letters are much to large.
The screenshot is on a 24inch monitor.

Preferences > Appearance > Override default font settings

That “Appearance” entry is always hidden, even when reducing the letter size. That I think is a very bad design decision since there is no indication that another list element is to be found. And the slider at the windows side is only evident when the mouse is over the slider. Sliders seem to be the problem, they should be more pronounced for they indicate there are things to be discoverd. My 5 €-cts.