--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -218,17 +218,21 @@ pref("dom.gamepad.haptic_feedback.enable
 // If this is true, TextEventDispatcher dispatches keydown and keyup events
 // even during composition (keypress events are never fired during composition
 // even if this is true).
 pref("dom.keyboardevent.dispatch_during_composition", false);
 
 // If this is true, TextEventDispatcher dispatches keypress event with setting
 // WidgetEvent::mFlags::mOnlySystemGroupDispatchInContent to true if it won't
 // cause inputting printable character.
+#ifdef EARLY_BETA_OR_EARLIER
+pref("dom.keyboardevent.keypress.dispatch_non_printable_keys_only_system_group_in_content", true);
+#else
 pref("dom.keyboardevent.keypress.dispatch_non_printable_keys_only_system_group_in_content", false);
+#endif
 
 // Whether the WebMIDI API is enabled
 pref("dom.webmidi.enabled", false);
 
 // Whether to run add-on code in different compartments from browser code. This
 // causes a separate compartment for each (addon, global) combination, which may
 // significantly increase the number of compartments in the system.
 pref("dom.compartment_per_addon", true);

--- a/widget/TextEventDispatcher.cpp
+++ b/widget/TextEventDispatcher.cpp
@@ -40,17 +40,17 @@ TextEventDispatcher::TextEventDispatcher
     Preferences::AddBoolVarCache(
       &sDispatchKeyEventsDuringComposition,
       "dom.keyboardevent.dispatch_during_composition",
       false);
     Preferences::AddBoolVarCache(
       &sDispatchKeyPressEventsOnlySystemGroupInContent,
       "dom.keyboardevent.keypress."
         "dispatch_non_printable_keys_only_system_group_in_content",
-      false);
+      true);
     sInitialized = true;
   }
 
   ClearNotificationRequests();
 }
 
 nsresult
 TextEventDispatcher::BeginInputTransaction(