This page hosts the disable-character-shortcuts Add-On for Thunderbird.

It can be used to stop the mail window's bare single-key shortcuts from firing by accident - the keys that act on the focused/selected message from a single keypress (a=archive, k=ignore thread, r=mark thread read, the tag keys 0-9, message navigation, etc.).

What it can do (all in the add-on's options)

• Character shortcuts - leave enabled, disable, or require a lead-in: press Ctrl+a chosen character first, then the shortcut key (within a short window). The set of character keys is auto-detected, so new ones are covered without an update.
• Delete / Backspace - optionally disable the message-deletion keys.
• Spacebar advance - optionally disable (toggles mail.advance_on_spacebar).
• Warn before opening many messages - optionally lower mailnews.open_tab_warning / open_window_warning so opening more than N messages at once (e.g. Enter on a multi-selection) asks for confirmation.

Menus, toolbar buttons, and any shortcut that uses a modifier (Ctrl/Cmd/Alt) are unaffected. Disabling restores cleanly when the add-on is disabled/removed.

To install:

• using your browser, RIGHT CLICK on the following link, and select SAVE AS
• save it to a file on your disk
• go to thunderbird, menu, Add-on and Themes
• click the gear icon and select "install from file"
• pick the file you have downloaded above
• if you're willing to accept the risk that this add-on could access any files on your computer, accept to install
• a page will open that allows you to configure the behavior

disable-character-shortcuts.xpi

This is an experimental add-on, no gurantees given, use at your own risk, MPL 2.0 license.