a) Whenever I change the screen fonts in the preferences
(typeface, zoom, etc.) and press "Apply", the new font seems to be
applied only partly. The spacing becomes strange, sometimes only
every second or third word appears in the new font. I have to save
the settings and restart LyX for the spacing to look "right". Is
this a known problem?
I can partly reproduce that effect. However, I avoid changing the
display fonts and I'm happy after all ;) - be patient, it'll surely
be fixed soon.
I had a similar problem. Quitting and restarting LyX after changing
the display fonts solved the problem.
Kevin