On 2013–08–20 Thangalin wrote:

> \showframe
> [
>   labels=on,
>   measurements=on,
>   color=red,
> ]
> 
> Would produce an image similar to the attached, but with the black
> lines drawn in the specified colour.
> 
> Using labels=on would show the names of the items that can be changed
> with \setuplayout.
> Using measurements=on would show the values for each of the items.
> 
> I don't know if there is any value separating the measurements from the labels.

Some years ago I visualised the layout elements for a cheat sheet. The code can be
found here:

  https://gist.github.com/mpfusion/4635387

It could be extended to visualise the layout dimensions as well. But
that complicates the code, since you don't know where the labels end
up and you need to check for overlapping labels.

Marco