[WPF] We want to virtualize ListViews
[WPF] We want to virtualize ListViews

This was off to autosize column headers to the full size, but we really need
a different behavior because we _need_ virtualization.

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