added 2632: block sites overriding FF KB shortcuts

Note: I tested the value of 1 when changing from 2-block to make sure that it actually changed to allow in the panel. Am keeping my eye on the delete and backspace keys and will remove the line when it is fixed

user.js

@@ -1299,6 +1299,10 @@ user_pref("accessibility.force_disabled", 1);
  * [WARNING] [SETUP] You may want to disable this for corporate or developer environments
  * [1] https://bugzilla.mozilla.org/show_bug.cgi?id=1343184 ***/
 user_pref("browser.tabs.remote.allowLinkedWebInFileUriProcess", false);
+/* 2632: disable websites overriding Firefox's keyboard shortcuts (FF58+)
+ * [SETTING] to add site exceptions: Page Info>Permissions>Override Keyboard Shortcuts
+ * [NOTE] At the time of writing, causes issues with delete and backspace keys ***/
+   // user_pref("permissions.default.shortcuts", 2); //  0 (default) or 1=allow, 2=block
 /* 2662: disable "open with" in download dialog (FF50+)
  * This is very useful to enable when the browser is sandboxed (e.g. via AppArmor)
  * in such a way that it is forbidden to run external applications.