There are many times that the right-click context menu doesn't come up, but you can press Ctrl+c and get at least some of the content onto the clipboard. I don't have DownloadHelper installed on this Firefox, but I think that's worth a try.

Ctrl+a to select all the selectable text on the page and Ctrl+c to copy it. Then try pasting into Notepad or another application. Any luck?

Ctrl+a works fine, but Ctrl+c doesn't copy anything to the clipboard.

I wonder why "click and drag the cursor" does not select text in Add-ons Manager? And why does Ctrl+c not work? Is there a security issue, or is it just a coding deficiency?

The right click context menu is a minor issue if I can at least easily select text and get it into the clipboard, DownloadHelper was just an example and where I ran into the issue--the problem seems to be in the Add-ons Manager and impacts all add-ons.

Thanks for your interest and answer.

Depending on what you want to copy, you could open the web page for that add-on and copy from there.

Oops, I just realized I was testing on a plugin, not an extension. I also find that Ctrl+c doesn't copy from the More page for an extension.

Okay, this is very hacky, but it seems to work to get a copyable display:

When viewing the extension's More page, press Ctrl+Shift+k to open Firefox's web console.

Then paste this code after the caret (») and press Enter to run it:

var tva = "<h1>" + document.querySelector("#detail-name").textContent + "</h1>"; var ddesc = document.querySelector("#detail-desc-container").innerHTML; ddesc = ddesc.replace(/\n/g, "<br>"); ddesc = ddesc.replace(/\<vbox|\<hbox/g, "<div"); ddesc = ddesc.replace(/\<\/vbox\>|\<\/hbox\>/g, "</div>\n"); ddesc = ddesc.replace(/\<description/g, "<p"); ddesc = ddesc.replace(/\<\/description\>/g, "</p>\n"); ddesc = ddesc.replace(/\<image/g, "<img"); ddesc = ddesc.replace(/\<\/image\>/g, ""); var wnew = window.open("", "_blank"); wnew.document.body.innerHTML = tva + ddesc;

A new tab (or window) should open with the description contents, retaining some level of HTML formatting.

Note that some texts are label elements that value a value attribute.

e=document.querySelectorAll("*");
for(i=0;E=e[i];i++){E.style.setProperty("-moz-user-select","text","important");E.style.setProperty("-moz-user-focus","normal","important");}

e=document.querySelectorAll("#detail-rows row");T=[];for(i=0;E=e[i];i++){L=[];if(E.hasAttribute("label")&&E.hasAttribute("value")){L.push(E.getAttribute("label"),E.getAttribute("value"));}else{f=E.querySelectorAll("label",".detail-row-label");for(j=0;F=f[j];j++){if(F.value!="undefined"){L.push(F.value);}else{L=[];}}}if(L)T.push(L)}
console.log(T.join("\n"));