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.

formfill-mode

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:

session_pref("browser.formfill.enable", false);

To re-enable it:

session_pref("browser.formfill.enable", true);