On 11 Dec 2020, at 08:21, Floris van Manen wrote:

On 11/12/2020 08:46, Jan U. Hasecke wrote:

...

as nobody answered I would like too repeat my question.

This is what I see

On a Mac running BigSur... 1) using the TeXShop built-in PDF viewer I see the word "yes" inside the box 2) in the 'Preview' app I see "yes" in the box 3) using Adobe Acrobat Reader DC I get: a) Initially a blank / grey box b) Hovering the mouse over the grey bit displays "yes" and the cursor changes from I-beam to hand c) Single clicking displays the word "yes" d) Move focus to another app and the word "yes" is replaced with a tick mark in the box e) Move focus back to Acrobat, hover over the box and the tick mark changes to "yes" f) Click the tick and the box changes to "yes" g) Move focus to another app and the box changes to blank i.e. unticked I've no idea whatsoever what to do about it or suggest which is why I didn't reply before. -- Bruce Horrocks Hampshire, UK