On Tue, 16 Jun 2020, Pablo Rodriguez wrote:

> On 6/16/20 4:58 PM, Wolfgang Schuster wrote:
>> Pablo Rodriguez schrieb am 16.06.2020 um 16:31:
>>> [...]
>>> I’m afraid that you get the same result, so there may be a bug there.
>>
>> There is no bug. When you take a look at my pagenumber example you see a
>> few lines at the top show the number of the previous page, this happens
>> because TeX collects more than necessary which means in your example
>> above the layer is placed when TeX was still on the first page.
>
> Many thanks for your reply, Wolfgang.
>
> I’m afraid that TeX is too tricky for me in that case (or I simply think
> that it is misbehaving there).
>
>> In your example you can add \testpage to \section to force a page break
>> when there isn't enough space available to place the heading, this moves
>> also the layer placement to the next page.
>
> I’m afraid this doesn’t work with my real document.
>
> I need another approach. This sample reflects my problem:
>
>  \setupinteraction[state=start]
>  %~ \showframe\showgrid
>  \starttext
>    \dorecurse{41}{one line\par}
>
>    \ \comment[location={rightmargin}]{comment}
>  \stoptext
>
> Since layers are problematic for the task, I insert the comments right
> after the text (which actually comes from \xmlflush{#1} [XML sources]).
>
> I’m afraid that the paragraph before \comment comes from \xmlflush, so I
> cannot avoid it.
>
> This is unproblematic for most cases, but the sample above displays the
> problem of adding a comment in a new paragraph. It might add a new page.
>
> To avoid this issue: how could I prevent the pagebreak before \comment
> and the addition of a pagebreak above?
>
> If that were possible, I could add a \blank[-2*line] that would place
> the comment right.

Try

\removeunwantedwhitespace

or

\blank[samepage]

Aditya