Interaction and button

In an interactive document it is useful to be able to put buttons which do specific navigation tasks. The \button does precisely this, and it can be included in a layer which can be put anywhere on a page. Here is an example:

\setuppapersize[A7][A7]
\setupinteraction[state=start]
\setupbodyfont[10pt]

\definelayer[MyButton]
	[width=\paperwidth,height=\paperheight]

\setlayerframed[MyButton]
	[x=30mm,y=40mm,
	location={lo,hi}]
	[width=50mm,height=30mm,
	%offset=-1mm,
	frame=on]
	{\button[frame=off]{\scale[height=2em]{\symbol[navigation 1][nextpage]}}[NextPage] \endgraf
	We have a nice button here}

\setupbackgrounds[page]
	[background={MyButton}]
\starttext
We have here a page with a layer containing a button.
\page
This is a second page, and here is a button to go back 
\button{\symbol[navigation 1][previouspage]}[PreviousPage].
\stoptext

This results in the following:

Indeed, instead of \symbol one can use any other character, or even a figure with the command \externalfigure.