Hmm, looks like a change to the eBay add-on, and there are several unhappy users posting in the reviews:

https://addons.mozilla.org/firefox/addon/ebay-sidebar/reviews/

When I look at the extension's Versions page, the next older version available is much older and possibly is obsolete, but if you want to try it, you can install it from here:

https://addons.mozilla.org/firefox/addon/ebay-sidebar/versions/

Does that one still work? If it does, although we encourage allowing updates in case there are security holes in an extension, you do have the ability to turn that off on the Add-ons page. Either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Extensions. Then find the eBay one on the right side. Click the small More link below the extension's title and on the details page, you can turn off updating for that extension.

Let us know what you learn.

Thanks jscher2000 for the suggestion of using an old version of eBay sidebar for Firefox (version 3.1.6.1-signed Dec 15 2014).

Although this did reposition the sidebar to the left, did not cover up page content underneath it and did not disappear completely whenever one clicks on an item, unfortunately it did not populate itself with my eBay data. 'Summary', 'Active', and 'Ended' did not work. The only thing that populated itself was 'eBay Deals' (stuff They suggest I might want to buy!), but even it did not open the item in a new tab when clicked upon.

I have had to remove the useless new eBay sidebar, as it takes more time using it than opening up pages manually using the 'my eBay' watch list - which does stay open, albeit in a separate tab. Then I can cut and paste from my watch list into various previously opened eBay search pages. From the same OVERALL time spent on eBay, I now spend half the time I previously did SEARCHING it, as far more time is spent manipulating data.