Using the TenFourFox preference pane

The TenFourFox preference pane controls features specific or useful for TenFourFox users. Some of these features are unique to TenFourFox. You should be using at least version 45.6 or later. Not all options appear in earlier versions of the browser.

To access the prefpane, go to the TenFourFox pull-down menu, select Preferences..., and in the new tab that opens click the TenFourFox tab on the left.

The MediaSource option controls whether MediaSource Extensions (MSE) are enabled.

• MSE allows the use of the more advanced VP9 video codec and allows sites to monitor and upgrade or downgrade your video quality dynamically, and may offer more video resolution options on certain sites such as YouTube. However, VP9 requires more computing resources to decode, and sites may select viewing resolutions your computer cannot handle. If this option is not checked, MSE is disabled, and the lower bitrate but faster VP8 codec is used instead.

• In general, very fast Power Macs and very slow Power Macs should use MSE; fast G5s can display in higher resolutions, and very slow Macs may have low bitrate options like 144p that are not available without MSE. Machines in the midrange, such as last-generation G4 systems, iBooks and PowerBooks, often should not.

• Here is more information about the best option for your system.

The PDF Viewing option controls whether the built-in PDF viewer is used.

• If this option is checked, TenFourFox uses a built-in PDF viewer. This viewer is written in JavaScript and is designed to be safer when viewing PDFs from unknown sources, but does not support many PDF features and may display certain documents incorrectly. It is also slower than Preview.app or Adobe Acrobat.

• If this option is unchecked, TenFourFox will usually offer to download the document, after which you can open it with Preview.app, Acrobat Reader, or other tools. This will display the document more quickly and correctly, but note that the document is not scanned for malware or other attempts to exploit flaws in the viewer, so it should not be used to view documents from unknown or suspicious sources.

The User Agent option controls how the user agent, the string the browser uses to identify itself, is set. This can affect how certain sites interact with the browser and what features they enable.

• If the default is selected, the default user agent for previous versions of TenFourFox is used, which is modeled on Firefox. It also includes the current build version as a token. Most sites will work fine with the default.

• The Firefox (Intel) options make your Power Mac appear to be an Intel Mac running Firefox, and carries no TenFourFox identification. This is most useful for banks and other secure sites which only claim to support certain specific browsers. You should pick the lowest numbered version the site will support.

• The other options may be useful for compatibility or performance on some sites. For example, the Classilla option uses the same user agent as the Classilla browser, which was specifically selected to prefer lightweight mobile content. This would be a good choice for a G3 system, for example.

• If at all possible, use the default option (TenFourFox); the others may cause sites to enable features the browser doesn't yet support or disable features that would otherwise work properly.

• Some sites, such as the TenFourFox Start Page, can determine you are using TenFourFox no matter what you have chosen for this setting.

The Adblock option controls basic adblock. If the Enable basic adblock option is checked, then the browser will block certain kinds of nuisance JavaScript, including many advertisements and ad-blocker-blockers, trackers, cryptominers, malware and spyware. Not only are these kinds of scripts obnoxious and sometimes dangerous, but blocking them also improves browser performance, sometimes substantially. Basic adblock is also faster at blocking such content than many adblock add-ons like Adblock Plus and uBlock Origin.

The default is unchecked (basic adblock is not on). You can enable and disable basic adblock as much as you like, though you may need to reload open tabs to suppress script content if the blockable scripts on the page have already started executing.

There are some important caveats with basic adblock:

• Not all advertising content is blocked. Basic adblock is just that: basic. There may be ad networks not yet covered by the blacklist, and advertising content that is not generated by JavaScript will still appear. Also, entries in the internal blacklist are chosen for quick filtering at the expense of false negatives. As a result, because some sites mix their advertising and site assets, some types of ads on these sites cannot be blocked easily without interfering with the site's functionality.

• Beacon images and tracking cookies that are not generated by JavaScript will still be loaded and can still be used to track you.

• Enabling basic adblock does not remove any stored information sites may have already acquired on your browsing history.

You can combine basic adblock with other blockers for enhanced security:

• If you open a Private Browsing window (Shift+Command+P) and have both Firefox Tracking Protection on (the default) and basic adblock on, then basic adblock is combined with the other privacy features of Private Browsing on sites you browse in that window, including additionally blocking many more kinds of tracking systems.

• If you have an adblocker extension such as uBlock Origin installed and also turn basic adblock on, then everything remaining that basic adblock does not block is then run through the adblocker extension. However, this is slower than using basic adblock alone.

• Yes, you can combine all three: if you have an adblocker extension, turn on basic adblock, and then open a Private Browsing window with Firefox Tracking Protection, then all three filters are active for the sites you browse in that window. This is, however, the slowest option.

For the fastest blocking experience, disable or remove any adblocker extension (as well as other unused extensions) before turning basic adblock on.

If you're not sure what these settings do, open a ticket on Tenderapp and we can help you.