[NTG-context] Height fitting cell contents while using row spanning in other columns of a table

How can I stretch the height of the x cell (in my example) to fit the x cell content? I have tried with extreme tables and natural tables but without success. \starttext With extreme tables (y cell content fitted by default):\crlf \startxtable \startxrow \startxcell[nr=2]\input knuth \stopxcell \startxcell x \stopxcell \stopxrow \startxrow \startxcell y \stopxcell \stopxrow \stopxtable With natural tables (no fit):\crlf \startTABLE \NC[nr=2]\input knuth \NC x \NC \NR \NC y \NC \NR \stopTABLE \stoptext