Extracting screen image from expriment

URL of experiment: Sign in · GitLab

Description of the problem: I am looking for a way to extract the screen image as a dataURL.
I have tried finding the html canvas and sending that to .toDataURL, niklasvh’s html2canavs to get a snapshot of the whole screen, and the PixiJS extracting api. But they all give me a blank image (that may be the background?).
I have the idea it is possible as I can manually save the screen image with a right click → save image, but it seems unable to do so in code.
Even using the inspect menu gives me no joy,
If anyone knows the route to get the renderer to output a dataURL as well as displaying to the screen, that would help no end.

Hey - as in you’de like the a screenshot of the page to ping back to pavlovia as a media file?