Link numbering is not a standard feature of Mozilla Firefox or a tool provided by Tobii. To use link numbering in Mozille Firefox, you need an Add-On called Mouseless Browsing. If the link numbers on your computer are not shown, this can be because of the following reasons:
1) Mouseless Browsing in Firefox is not installed
To install the Add-on go to: https://addons.mozilla.org/en-us/firefox/addon/mouseless-browsing/
2) Mouseless Browsing in Firefox is disabled
To enable mouseless browsing: Open Firefox - Tools - Mouseless browsing - uncheck disable MLB
3) Mouseless Browsing is not (yet) compatible with the Firefox version you have installed
Mozilla has been releasing many new versions lately which makes it difficult for Add-On developers to keep their software compatible. Each new Firefox release requires them to test and possibly update their add-ons. If you wait a while, mouseless browsing will most likely get a new update soon. An alternative is to downgrade to an earlier version of Firefox. It is recommendable to subscribe to the Firefix Extended Support Release (ESR) instead. The ESR releases happen less frequently and give developers more time to adopt their software. You can download the latest Firefox ESR directly from Mozilla: http://www.mozilla.org/en-US/firefox/organizations/all.html
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