[DomKey X11] Produce correct DomKey when Control is down

third_party/WebKit/Source/core/editing/EditingBehavior.cpp

 /*
  * Copyright (C) 2006, 2007 Apple, Inc.  All rights reserved.
  * Copyright (C) 2012 Google, Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 249 matching lines @@
   // send ASCII characters when pressing a control key on Windows,
   // which may be configured to do it so by user.
   // See also http://en.wikipedia.org/wiki/Keyboard_Layout
   // FIXME(ukai): investigate more detail for various keyboard layout.
   UChar ch = event.keyEvent()->text[0U];
 
   // Don't insert null or control characters as they can result in
   // unexpected behaviour
   if (ch < ' ')
     return false;
-#if !OS(WIN)
+#if OS(LINUX)
+  // According to XKB map no keyboard combinations with ctrl key are mapped to
+  // printable characters, however we need the filter as the DomKey/text could
+  // contain printable characters.
+  if (event.ctrlKey())

[yosin_UTC9, 2016/11/11 01:49:26]

Q: How about other modifier keys, Alt, Meta, Hyper, etc?

[chongz, 2016/11/11 20:12:28]

Good question!
  1. Alt: We set |webkit_event.isSystemKey = true| when Alt is down, so it
should never go into here.
    * See "web_input_event.cc::MakeWebKeyboardEventFromUiEvent()"
  2. Meta, Hyper: From my testing these keys don't affect the produced character
on native apps (such as gedit) , otherwise we can fix it later if we found
exceptions.

+    return false;
+#elif !OS(WIN)
   // Don't insert ASCII character if ctrl w/o alt or meta is on.
   // On Mac, we should ignore events when meta is on (Command-<x>).
   if (ch < 0x80) {
     if (event.ctrlKey() && !event.altKey())
       return false;
 #if OS(MACOSX)
     if (event.metaKey())
       return false;
 #endif
   }
 #endif
 
   return true;
 }
 }  // namespace blink