fix #3500 crash after close any fullscreen window  on mac
fix #3500 crash after close any fullscreen window  on mac

wieslawsoltes/Perspex,AvaloniaUI/Avalonia,SuperJMN/Avalonia,wieslawsoltes/Perspex,AvaloniaUI/Avalonia,SuperJMN/Avalonia,jkoritzinsky/Avalonia,wieslawsoltes/Perspex,grokys/Perspex,SuperJMN/Avalonia,jkoritzinsky/Perspex,AvaloniaUI/Avalonia,SuperJMN/Avalonia,AvaloniaUI/Avalonia,Perspex/Perspex,grokys/Perspex,wieslawsoltes/Perspex,jkoritzinsky/Avalonia,SuperJMN/Avalonia,jkoritzinsky/Avalonia,jkoritzinsky/Avalonia,wieslawsoltes/Perspex,SuperJMN/Avalonia,AvaloniaUI/Avalonia,akrisiun/Perspex,AvaloniaUI/Avalonia,SuperJMN/Avalonia,jkoritzinsky/Avalonia,wieslawsoltes/Perspex,jkoritzinsky/Avalonia,wieslawsoltes/Perspex,Perspex/Perspex,AvaloniaUI/Avalonia,jkoritzinsky/Avalonia