>> So in the absence of any font metrics or font identification,
>> what would you suggest?
>
>Perhaps getting away from overly long button text?! ;^)
>
Yes, a comparison between KDE and Windows will show everyone what 
Usable gUi-programming means: Make texts short and have only few items 
per widget or window. This way the user can choose a bigger font 
without exploding his screen. Given this criterion I rate KDE best. To 
choose the smallest available font is no real solution. And to pretend 
that the user can choose all fonts, and then come up all the time with 
one being completely out of place, well, that's Windows. 

Regards
Martin