[NTG-context] Specifying maximum width of a frame

Hi, I want to specify the maximum width of a frame. If the size of the box is smaller than the maximum width, I want a tight box. Something like \frame[maxwidth=5cm,align=middle]{Small} should give +-----+ |small| +-----+ while \frame[maxwidth=5cm,align=middle]{A very very long line that is split at 5cm} should give +----------------------+ | A very very long | | line that is split | | at 5cm | +----------------------+ Is there something builtin that does this, or do I need to play with scratchbox cum suis. Aditya