Accessibility.warn on browsewithcaret
From MozillaZine Knowledge Base
Originally for debugging purposes, caret browsing is provided as a way to navigate through a web page—using only the keyboard—by moving a text caret. This mode is easily toggled by pressing [F7]. However, it was found that users would accidentally hit [F7] without knowing its effects, and then wonder why a blinking cursor appeared on every page. This preference determines whether or not a dialog box will be shown when entering caret browsing mode via [F7].
Possible values and their effects
Each time [F7] is pressed, display a dialog box warning the user that they are entering Caret Browsing mode.
Never show a dialog before entering Caret Browsing mode.
This preference can be set by checking the "Do not show me this dialog box again" checkbox on the "Caret Browsing" dialog that appears the first time [F7] is pressed.
First checked in
Has an effect in