[Conkeror] carriage return - context sensitivity

[Silvio Levy]

I like to have carriage-return scroll back, so I wrote

define_key(content_buffer_normal_keymap, "return", "cmd_movePageUp");

in my RC file.  This makes it act weird when filling in forms.  But
the mode when filling in a form is presumably different - for instance,
in content_buffer_normal_keymap I bind "j" to "cmd_scrollLineDown",
but in filling a form the "j" key inserts a j.

Any suggestions?  

Silvio