In the Editor Preferences section of the developer tools settings, you can choose to use Vim, Emacs, or Sublime Text key bindings instead.
To select these, visit about:config, select the setting devtools.editor.keymap, and assign "vim" or "emacs", or "sublime" to that setting. If you do this, the selected bindings will be used for all the developer tools that use the source editor. You need to reopen the editor for the change to take effect.
From: https://developer.mozilla.org/en/docs/Tools/Scratchpad
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