[WPF] Widget allocation optimization
[WPF] Widget allocation optimization

Box: Only measure the child widget when it is first added to the box.

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