System fonts became so big after latest virtualbox update

Question

I'm running Arch Linux 64 as a guest on a Windows 7 host, with Virtualbox 4.3.28. After upgrade from May 19, systems fonts suddenly became so big (at least tripled). I am a newbie here, don't know how to attach a screen shot.
I've narrowed down to these 2 package upgrades:
community/virtualbox-guest-modules 4.3.26-7 -> 4.3.28-1
community/virtualbox-guest-utils   4.3.26-3 -> 4.3.28-1
If I skip these 2 package upgrades, and all other packages upgraded to the latest (including Linux to 4.0.4), the fonts are normal.

Answer 1

This problem seems a little complicated. It is related to screen resolution but strangely. On W7
1) if I shrink the screen resolution smaller, say 1024x768, and stay with this small screen, the fonts are normal everywhere. 
2) When boot up the VM, I cannot use a large resolution like 1920x1200 (as my VM was running under before the recent virtualbox packages upgrade). Otherwise, all fonts become so huge. So I detoured this out by booting in small resolution.
3) After booting up in small resolution, if I increase the resolution, say back to 1920x1200, the fonts on the console (my case terminator) stay fine. However, when I start applications like Sublime Text, Claws mail, the fonts on those applications' menu bar become so huge. The fonts inside Sublime Text are normal. But the fonts inside Claws mail are huge too.
4) After booting up in small resolution, if first start up the applications, then increase the resolution, say back to 1920x1200, all fonts are fine everywhere.