The following I wrote to initially question why showing dom properties didn't work at all, but I only had tried it on an textarea example on developer.mozilla.org so far. Turns out, on right this support forum's textarea I'm right now writing in, it does work. Could I make it work on developer.mozilla.org, too, like it works here on support.mozilla.org? That would be useful to inspect the html and javascript examples on there. Original planned question: I very recently updated to Firefox 91.3.0esr (64-Bit), and I restarted working with the developer tools. As far as I can recall it was possible to see an overview of an html page's element's functions somewhere in the developer tools. I tried "Untersuchen (Q)" ("Examine" or is it "Inspect" in English) on the textarea (in https://developer.mozilla.org/en-US/docs/Web/API/HTMLTextAreaElement ). This openend the developer tools panel, the html was shown and the textarea-elemtent highlighted. There I right clicked and selected "Dom-Eigenschaften anzeigen" (View dom properties). The console opened, and showed: ''inspect($0, true) Restricted { }'' (I want to access all the scroll properties of the textarea, and possible functions to scroll the textarea using javascript.) Under the settings page of the developer tools -> standard developer tools -> I actived the checkbox "DOM", and restarted the browser (using the restart option under about:profiles).