[Box] Don't return negative values when calculating the preferred size
[Box] Don't return negative values when calculating the preferred size

mminns/xwt,lytico/xwt,directhex/xwt,cra0zy/xwt,sevoku/xwt,mminns/xwt,hamekoz/xwt,antmicro/xwt,residuum/xwt,mono/xwt,hwthomas/xwt,steffenWi/xwt,akrisiun/xwt,iainx/xwt,TheBrainTech/xwt