[NTG-context] redifining font sizes

Hi there, using the latest beta, I have tried to change the x font size from 0.8 to 0.9, but it doesn't work. Here is a minimal sample: \definefontsize[w] \setupbodyfontenvironment[default][w=0.9, x=0.9] \starttext a {\tfx a} {\tfw a} \stoptext Why isn't the x font size set to 0.9? Many thanks for your help, Pablo -- http://www.ousia.tk