Changes

\setuppapersize[A10A7]

\setupbackgrounds[footer] [background=color, backgroundcolor=blue]\setupbackgrounds[footer] [leftmargin] [background=color, backgroundcolor=red]\setupbackgrounds [text] [background=color, backgroundcolor=lightgray]\setupbackgrounds [text] [rightmargin] [background=color, backgroundcolor=yellow]

\setupbackgroundsstarttextI paint modern\stoptext</context> === Example of dynamic positioning of page numbering === <context source=yes>\setuppapersize[textA6] [background=color, backgroundcolor=lightgrayA6]\setupbackgrounds[textstate=repeat] [rightmargin] [background%\showframe\startuseMPgraphic{MonGraphismeV_MP} numeric h ; h := \overlayheight ; numeric w ; w := \overlaywidth ; numeric n ; n := \number\realpageno ; numeric m ; m := \number\lastpageno ; numeric ratio ; ratio := (1-n/(m+1)); numeric e ; e := 0.3mm;  picture pa ; pa := textext.raw(btex {\strut\the\realpageno} etex) ; numeric wpa ; wpa := xpart (urcorner pa - ulcorner pa); numeric hpa ; hpa := ypart (ulcorner pa - llcorner pa);  pa := pa shifted (-wpa/2 + w/2, ratio * (h-hpa)); pair paA ; paA:= ((ulcorner pa) + (urcorner pa)) / 2 ; pair paB ; paB:=color((llcorner pa) + (lrcorner pa)) / 2 ;  draw ((w/2, backgroundcolor0)--paB) dashed withdots withpen pencircle scaled e withcolor darkred; draw ((w/2,h)--paA) dashed withdots withpen pencircle scaled e withcolor darkred; draw pa withcolor darkred;\stopuseMPgraphic \startuseMPgraphic{MonGraphismeH_MP} numeric h ; h := \overlayheight ; numeric w ; w :=yellow]\overlaywidth ; numeric n ; n := \number\realpageno ; numeric m ; m := \number\lastpageno ; numeric ratio ; ratio := (n/(m+1)); numeric e ; e := 0.3mm;

I paint modern picture pa ; pa := textext.raw(btex {\strut\the\realpageno} etex) ; numeric wpa ; wpa := xpart (urcorner pa - ulcorner pa); numeric hpa ; hpa := ypart (ulcorner pa - llcorner pa);  pa := pa shifted (ratio * (w-wpa),-hpa/2 + h/2); pair paA ; paA:= ((ulcorner pa) + (llcorner pa)) / 2 ; pair paB ; paB:= ((urcorner pa) + (lrcorner pa)) / 2 ;  draw ((0,h/2)--paA) dashed withdots withpen pencircle scaled e withcolor darkred; draw ((w,h/2)--paB) dashed withdots withpen pencircle scaled e withcolor darkred; draw pa withcolor darkred;\stopuseMPgraphic \defineoverlay [MonGraphismeV_OL] [\useMPgraphic{MonGraphismeV_MP}]\defineoverlay [MonGraphismeH_OL] [\useMPgraphic{MonGraphismeH_MP}] \setupbackgrounds [text] [rightmargin] [background={MonGraphismeV_OL}]\setupbackgrounds [footer] [text] [background={MonGraphismeH_OL}] \starttext \dorecurse{4}{\input tufte\page} \stoptext