Allow negative Thickness values.
Allow negative Thickness values.

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