From MozillaZine Knowledge Base
The backspace key was mapped to the browser â€˜Backâ€™ function in Mozilla for consistency with Internet Explorer. However, to improve consistency with other applications running on Linux, it was decided that this mapping should be optionalâ€”and set based on which platform the browser was running on. As a compromise, this preference was created to allow the backspace key to either go back/forward, scroll up/down a page, or do nothing.
Possible values and their effects
Pressing [Backspace] will go back a page in the session history and [Shift]+[Backspace] will go forward. (Default in Windows)
Pressing [Backspace] will scroll up a page in the current document and [Shift]+[Backspace] will scroll down. (Default in Linux builds before 2006-12-07)
Any other integer value will simply unmap the backspace key. In Linux builds after 2006-12-07, the default is 2.
First checked in
Has an effect in