[WPF] Use 0 for TreeView preferred size
[WPF] Use 0 for TreeView preferred size

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