Not a question, but a solution to unwanted thumbnails appearing in new tab.
I have been forced to create a new profile because, after an update to version 17.0, Firefox persisted in opening tabs from the previous session. Unfortunately another problem developed, namely, the constant appearance of a series of thumbnails in a new tab, a facility that I definitely do not want. After consulting Mozilla help and forums I tried all of the suggested solutions to no avail.
I eventually went about:config browser.newtabpage.enabled and rendered it false. The annoying thumbnails have disappeared!!!!!