[NTG-context] Labelling with textext

I'm trying to typeset a numerical label (in math mode) and have space for a - sign (but not actually typeset the -) after the number in the case where the number itself is negative. I am trying this label.bot(textext("$" & decimal(x) & "\hphantom{-}$"),(x*u,ay*u)); which fails. If I remove the \hphantom command, i.e., label.bot(textext("$" & decimal(x) & "$"),(x*u,ay*u)); the command is successful, but the number being labeled is not exactly horizontally centered below the point in question since the - symbol preceding the number pushes it a little to the right. Thoughts on how to achieve my desired \hphantom effect? Thanks, -- Troy Henderson Assistant Professor Department of Mathematics University of Mobile http://www.tlhiv.org