Formfill is the feature that provides a popup list of completions for input fields in content. The completions are things that you have previously entered into this or similar form fields.
Although the popup itself is managed by Mozilla, Conkeror provides a thin wrapper called formfill-mode that becomes enabled whenever the formfill popup is showing, and provides key combos to work with the popup.
The keys C-n and C-p select the next and previous item from the formfill popup, respectively.
Enabling and Disabling Formfill
Formfill is enabled by default. To disable it, put the following in your rc:
To re-enable it: