https://support.mozilla.org/en-US/kb/hide-or-display-sites-new-tab-page

You can create this Boolean pref on the about:config page to prevent Firefox from generating thumbnails for the about:newtab page.

• browser.pagethumbnails.capturing_disabled = true

Delete the thumbnails folder in the Firefox profile folder to remove already stored web page thumbnails.

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

You can use this button to go to the current Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

• https://developer.mozilla.org/Mozilla/Preferences/Preference_reference/browser.pagethumbnails.capturing_disabled

Thank you cor-el. That gets halfway there. Any ideas on how to remove the captions as well so that there is no data capture and a newtab displays grey dashed areas only?

What is this gooble-gook that is saved under 'browser.newtabpage.blocked'?

Looks like 'asDAsdfaASDASASAjkljkli==:1'.

And they are stored in a text file. They are somehow related to tiles.

Why are these being stored?

TL;DR:

Backup you profile folder just in case Firefox gets messed up.

Solution seems to be to copy omni.ja to another directory of your choice, rename omni.ja to omni.zip, extract omni.zip, open 'DirectoryLinksProvider.jsm' in 'modules' directory (seems to be the only one that matters), blank it, save it, recompress all extracted files using correct settings (tricky!) into omni.zip again, rename omni.zip into omni.ja, move and backup the original omni.ja elsewhere, and copy in its place this new omni.ja with all changes included. Finally, disable an addon that requires a restart, restart and reenable it again and restart again. Firefox should run without tiles. From experience, a search bar and customize newtab button appear in a newtab but they were non-functional.

Full instructions:

To do later. Maybe.

For the impatient maybe glean more from the following links:

https://developer.mozilla.org/en-US/docs/Mozilla/About_omni.ja_%28formerly_omni.jar%29 http://forums.mozillazine.org/viewtopic.php?f=27&t=2637857 https://support.mozilla.org/en-US/questions/1057798 https://support.mozilla.org/en-US/questions/1050290 https://support.mozilla.org/en-US/questions/973320 https://support.mozilla.org/en-US/questions/983090 https://support.mozilla.org/en-US/questions/1072480

browser.newtabpage.blocked stores the MD5 hashes of website you have blocked on the about:newtab page.

Note that modifying omni.ja archives is likely to trigger a full update and you would have to repeat these edits once again.

If you want to remove the sponsored directory links on the about:newtab page then use these steps: You can set the browser.newtabpage.directory.source pref to an empty string on the about:config page.

• browser.newtabpage.directory.source = <empty>
• browser.newtabpage.directory.ping = <empty>

You can delete the directoryLinks.json file in the parent location of the disk cache to remove the currently stored directory links.

• delete directoryLinks.json

See the about:cache page for the location of the disk cache and go one level up.

Thank you again cor-el. That was useful to know.

On updating, Firefox is not set to automatically update. And so far it seems to be working fine.