[NTG-context] underbar to space

Hi, I just want to do \underbar{\ \ \ \ \ \ \ \ \ \ .... \ } for doing something like: __________________ . When I do that ConTeXt does not underbar me the spaces. The same applies for \underbar{\space \space \space } How can I get that \underbar underbars the spaces even? Thanks in advance, Xan. PS: Please CC mail me.