Add Popup PlacementMode Center: measure popup child according to placement target instead of popup root.
Add Popup PlacementMode Center: measure popup child according to placement target instead of popup root.

akrisiun/Perspex,SuperJMN/Avalonia,wieslawsoltes/Perspex,jkoritzinsky/Avalonia,susloparovdenis/Avalonia,OronDF343/Avalonia,jkoritzinsky/Avalonia,jkoritzinsky/Avalonia,AvaloniaUI/Avalonia,susloparovdenis/Avalonia,jkoritzinsky/Avalonia,AvaloniaUI/Avalonia,AvaloniaUI/Avalonia,susloparovdenis/Perspex,grokys/Perspex,AvaloniaUI/Avalonia,jkoritzinsky/Avalonia,MrDaedra/Avalonia,jazzay/Perspex,jkoritzinsky/Perspex,AvaloniaUI/Avalonia,MrDaedra/Avalonia,Perspex/Perspex,jkoritzinsky/Avalonia,grokys/Perspex,wieslawsoltes/Perspex,susloparovdenis/Perspex,SuperJMN/Avalonia,SuperJMN/Avalonia,Perspex/Perspex,SuperJMN/Avalonia,wieslawsoltes/Perspex,wieslawsoltes/Perspex,jkoritzinsky/Avalonia,OronDF343/Avalonia,SuperJMN/Avalonia,punker76/Perspex,AvaloniaUI/Avalonia,wieslawsoltes/Perspex,SuperJMN/Avalonia,AvaloniaUI/Avalonia,wieslawsoltes/Perspex,SuperJMN/Avalonia,wieslawsoltes/Perspex