FWIW, I have come around about the fonts ;-)

I have been using Open Sans & Source Code Pro for a while now, and I like them.

These are my font selections for my MacBook Air 13�� (1440x900):

Light and modern, like Pharo itself !

Apart from the bolding of the window title font, this code sets those fonts:

SourceCodeProRegular new install.
OpenSansRegular new install.
FreeTypeFontProvider current updateFromSystem.

#(
#(#defaultFont: 'Open Sans' 12) 
#(#listFont: 'Open Sans' 12) 
#(#menuFont: 'Open Sans' 12) 
#(#windowTitleFont: 'Open Sans' 12) 
#(#balloonFont: 'Open Sans' 10) 
#(#codeFont: 'Source Code Pro' 11) 
#(#buttonFont: 'Open Sans' 12) 
#(#haloFont: 'Open Sans' 10)) do: [ :spec | 
| font |
font := LogicalFont familyName: spec second pointSize: spec third.
StandardFonts perform: spec first with: font ]

Thanks again for taking care !

Sven