diff --git a/app/ui/backup.py b/app/ui/backup.py
index 3b20fcf5..768ed22a 100644
--- a/app/ui/backup.py
+++ b/app/ui/backup.py
@@ -2,7 +2,7 @@
 #
 # The MIT License (MIT)
 #
-# Copyright (c) 2018-2024 Dmitriy Yefremov
+# Copyright (c) 2018-2026 Dmitriy Yefremov
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to deal
@@ -223,11 +223,11 @@ class BackupDialog:
             self._settings.add("backup_tool_window_size", window.get_size())
 
     def on_key_release(self, view, event):
-        """  Handling  keystrokes  """
-        key_code = event.hardware_keycode
-        if not KeyboardKey.value_exist(key_code):
+        """  Handling  keystrokes.  """
+        key = KeyboardKey(event.hardware_keycode)
+        if key is KeyboardKey.UNDEFINED:
             return
-        key = KeyboardKey(key_code)
+
         ctrl = event.state & MOD_MASK
 
         if key is KeyboardKey.DELETE:
diff --git a/app/ui/epg/epg.py b/app/ui/epg/epg.py
index b17d5633..930fc212 100644
--- a/app/ui/epg/epg.py
+++ b/app/ui/epg/epg.py
@@ -1217,10 +1217,10 @@ class EpgDialog:
 
     def on_key_press(self, view, event):
         """  Handling  keystrokes  """
-        key_code = event.hardware_keycode
-        if not KeyboardKey.value_exist(key_code):
+        key = KeyboardKey(event.hardware_keycode)
+        if key is KeyboardKey.UNDEFINED:
             return
-        key = KeyboardKey(key_code)
+
         ctrl = event.state & Gdk.ModifierType.CONTROL_MASK
 
         if ctrl and key is KeyboardKey.C:
diff --git a/app/ui/ftp.py b/app/ui/ftp.py
index c85618a7..c31b1317 100644
--- a/app/ui/ftp.py
+++ b/app/ui/ftp.py
@@ -2,7 +2,7 @@
 #
 # The MIT License (MIT)
 #
-# Copyright (c) 2018-2025 Dmitriy Yefremov
+# Copyright (c) 2018-2026 Dmitriy Yefremov
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to deal
@@ -856,11 +856,10 @@ class FtpClientBox(Gtk.HBox):
             self._settings.ftp_bookmarks = [r[0] for r in self._bookmark_model]
 
     def on_view_key_press(self, view, event):
-        key_code = event.hardware_keycode
-        if not KeyboardKey.value_exist(key_code):
+        key = KeyboardKey(event.hardware_keycode)
+        if key is KeyboardKey.UNDEFINED:
             return
 
-        key = KeyboardKey(key_code)
         ctrl = event.state & MOD_MASK
 
         if key is KeyboardKey.F7:
diff --git a/app/ui/imports.py b/app/ui/imports.py
index 86f009b2..7c071e01 100644
--- a/app/ui/imports.py
+++ b/app/ui/imports.py
@@ -426,10 +426,9 @@ class ImportDialog:
 
     def on_key_press(self, view, event):
         """  Handling  keystrokes  """
-        key_code = event.hardware_keycode
-        if not KeyboardKey.value_exist(key_code):
+        key = KeyboardKey(event.hardware_keycode)
+        if key is KeyboardKey.UNDEFINED:
             return
-        key = KeyboardKey(key_code)
 
         if key is KeyboardKey.SPACE:
             model = view.get_model()
diff --git a/app/ui/iptv.py b/app/ui/iptv.py
index 9564b28f..36896b1f 100644
--- a/app/ui/iptv.py
+++ b/app/ui/iptv.py
@@ -2,7 +2,7 @@
 #
 # The MIT License (MIT)
 #
-# Copyright (c) 2018-2025 Dmitriy Yefremov
+# Copyright (c) 2018-2026 Dmitriy Yefremov
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to deal
@@ -1331,10 +1331,9 @@ class YtListImportDialog:
         view.get_model().foreach(lambda mod, path, itr: mod.set_value(itr, 2, select))
 
     def on_key_press(self, view, event):
-        key_code = event.hardware_keycode
-        if not KeyboardKey.value_exist(key_code):
+        key = KeyboardKey(event.hardware_keycode)
+        if key is KeyboardKey.UNDEFINED:
             return
-        key = KeyboardKey(key_code)
 
         if key is KeyboardKey.SPACE:
             path, column = view.get_cursor()
diff --git a/app/ui/main.py b/app/ui/main.py
index 86d4c4b9..aebe1d16 100644
--- a/app/ui/main.py
+++ b/app/ui/main.py
@@ -2975,11 +2975,10 @@ class Application(Gtk.Application):
 
     def on_tree_view_key_press(self, view, event):
         """  Handling  keystrokes on press """
-        key_code = event.hardware_keycode
-        if not KeyboardKey.value_exist(key_code):
-            return
+        key = KeyboardKey(event.hardware_keycode)
+        if key is KeyboardKey.UNDEFINED:
+            return False
 
-        key = KeyboardKey(key_code)
         ctrl = event.state & MOD_MASK
         if key is KeyboardKey.F:
             if ctrl:
@@ -3028,11 +3027,10 @@ class Application(Gtk.Application):
 
     def on_tree_view_key_release(self, view, event):
         """  Handling  keystrokes on release """
-        key_code = event.hardware_keycode
-        if not KeyboardKey.value_exist(key_code):
+        key = KeyboardKey(event.hardware_keycode)
+        if key is KeyboardKey.UNDEFINED:
             return
 
-        key = KeyboardKey(key_code)
         ctrl = event.state & MOD_MASK
         shift = event.state & Gdk.ModifierType.SHIFT_MASK
         model_name, model = get_model_data(view)
@@ -4539,11 +4537,10 @@ class Application(Gtk.Application):
                 self.emit("fav-changed", srv)
 
     def on_alt_view_key_press(self, view, event):
-        key_code = event.hardware_keycode
-        if not KeyboardKey.value_exist(key_code):
+        key = KeyboardKey(event.hardware_keycode)
+        if key is KeyboardKey.UNDEFINED:
             return
 
-        key = KeyboardKey(key_code)
         ctrl = event.state & MOD_MASK
 
         if ctrl and key == KeyboardKey.V:
diff --git a/app/ui/picons.py b/app/ui/picons.py
index 9a8c5b55..168d3f69 100644
--- a/app/ui/picons.py
+++ b/app/ui/picons.py
@@ -2,7 +2,7 @@
 #
 # The MIT License (MIT)
 #
-# Copyright (c) 2018-2024 Dmitriy Yefremov
+# Copyright (c) 2018-2026 Dmitriy Yefremov
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to deal
@@ -976,11 +976,10 @@ class PiconManager(Gtk.Box):
         return True
 
     def on_tree_view_key_press(self, view, event):
-        key_code = event.hardware_keycode
-        if not KeyboardKey.value_exist(key_code):
+        key = KeyboardKey(event.hardware_keycode)
+        if key is KeyboardKey.UNDEFINED:
             return
 
-        key = KeyboardKey(key_code)
         if key is KeyboardKey.DELETE:
             self.on_local_remove(view)
 
diff --git a/app/ui/recordings.py b/app/ui/recordings.py
index 599f398e..50d261be 100644
--- a/app/ui/recordings.py
+++ b/app/ui/recordings.py
@@ -304,11 +304,10 @@ class RecordingsTool(Gtk.Box):
         self._filter_entry.grab_focus() if button.get_active() else self._filter_entry.set_text("")
 
     def on_recordings_key_press(self, view, event):
-        key_code = event.hardware_keycode
-        if not KeyboardKey.value_exist(key_code):
+        key = KeyboardKey(event.hardware_keycode)
+        if key is KeyboardKey.UNDEFINED:
             return
 
-        key = KeyboardKey(key_code)
         if key is KeyboardKey.DELETE:
             self.on_recording_remove()
 
diff --git a/app/ui/telnet.py b/app/ui/telnet.py
index a453c9ee..a94eaacd 100644
--- a/app/ui/telnet.py
+++ b/app/ui/telnet.py
@@ -2,7 +2,7 @@
 #
 # The MIT License (MIT)
 #
-# Copyright (c) 2018-2025 Dmitriy Yefremov
+# Copyright (c) 2018-2026 Dmitriy Yefremov
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to deal
@@ -129,11 +129,10 @@ class TelnetClient(Gtk.Box):
             self.do_command()
             return True
 
-        key_code = event.hardware_keycode
-        if not KeyboardKey.value_exist(key_code):
-            return None
+        key = KeyboardKey(event.hardware_keycode)
+        if key is KeyboardKey.UNDEFINED:
+            return False
 
-        key = KeyboardKey(key_code)
         ctrl = event.state & MOD_MASK
         if ctrl and key is KeyboardKey.C:
             if self._tn and self._tn.sock:
diff --git a/app/ui/timers.py b/app/ui/timers.py
index 177c750a..b962ee04 100644
--- a/app/ui/timers.py
+++ b/app/ui/timers.py
@@ -2,7 +2,7 @@
 #
 # The MIT License (MIT)
 #
-# Copyright (c) 2018-2024 Dmitriy Yefremov
+# Copyright (c) 2018-2026 Dmitriy Yefremov
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to deal
@@ -460,11 +460,10 @@ class TimerTool(Gtk.Box):
             on_popup_menu(menu, event)
 
     def on_timers_key_release(self, view, event):
-        key_code = event.hardware_keycode
-        if not KeyboardKey.value_exist(key_code):
+        key = KeyboardKey(event.hardware_keycode)
+        if key is KeyboardKey.UNDEFINED:
             return
 
-        key = KeyboardKey(key_code)
         ctrl = event.state & MOD_MASK
 
         if key is KeyboardKey.DELETE:
diff --git a/app/ui/uicommons.py b/app/ui/uicommons.py
index 397096ca..802e768e 100644
--- a/app/ui/uicommons.py
+++ b/app/ui/uicommons.py
@@ -2,7 +2,7 @@
 #
 # The MIT License (MIT)
 #
-# Copyright (c) 2018-2025 Dmitriy Yefremov
+# Copyright (c) 2018-2026 Dmitriy Yefremov
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to deal
@@ -290,14 +290,8 @@ class Column(IntEnum):
 
 # *************** Keyboard keys *************** #
 
-class BaseKeyboardKey(Enum):
-    @classmethod
-    def value_exist(cls, value):
-        return value in (val.value for val in cls.__members__.values())
-
-
 if IS_LINUX:
-    class KeyboardKey(BaseKeyboardKey):
+    class KeyboardKey(IntEnum):
         """ The raw(hardware) codes [Linux] of the keyboard keys. """
         E = 26
         R = 27
@@ -335,8 +329,14 @@ if IS_LINUX:
         PAGE_UP_KP = 81
         PAGE_DOWN_KP = 89
 
+        UNDEFINED = -1
+
+        @classmethod
+        def _missing_(cls, value):
+            return cls.UNDEFINED
+
 elif IS_DARWIN:
-    class KeyboardKey(BaseKeyboardKey):
+    class KeyboardKey(IntEnum):
         """ The raw(hardware) codes [macOS] of the keyboard keys. """
         F = 3
         E = 14
@@ -376,8 +376,14 @@ elif IS_DARWIN:
         PAGE_UP_KP = -1
         PAGE_DOWN_KP = -1
 
+        UNDEFINED = -1
+
+        @classmethod
+        def _missing_(cls, value):
+            return cls.UNDEFINED
+
 else:
-    class KeyboardKey(BaseKeyboardKey):
+    class KeyboardKey(IntEnum):
         """ The raw(hardware) codes [Windows] of the keyboard keys. """
         E = 69
         R = 82
@@ -415,6 +421,12 @@ else:
         PAGE_UP_KP = -1
         PAGE_DOWN_KP = -1
 
+        UNDEFINED = -1
+
+        @classmethod
+        def _missing_(cls, value):
+            return cls.UNDEFINED
+
 # Keys for move in lists. KEY_KP_(NAME) for laptop!
 MOVE_KEYS = {KeyboardKey.UP, KeyboardKey.PAGE_UP,
              KeyboardKey.DOWN, KeyboardKey.PAGE_DOWN,
diff --git a/app/ui/xml/edit.py b/app/ui/xml/edit.py
index d374a1a2..859f5dd6 100644
--- a/app/ui/xml/edit.py
+++ b/app/ui/xml/edit.py
@@ -2,7 +2,7 @@
 #
 # The MIT License (MIT)
 #
-# Copyright (c) 2018-2025 Dmitriy Yefremov
+# Copyright (c) 2018-2026 Dmitriy Yefremov
 #
 # Permission is hereby granted, free of charge, to any person obtaining a copy
 # of this software and associated documentation files (the "Software"), to deal
@@ -310,11 +310,10 @@ class SatellitesTool(Gtk.Box):
 
     def on_key_press(self, view, event):
         """ Handling  keystrokes. """
-        key_code = event.hardware_keycode
-        if not KeyboardKey.value_exist(key_code):
+        key = KeyboardKey(event.hardware_keycode)
+        if key is KeyboardKey.UNDEFINED:
             return
 
-        key = KeyboardKey(key_code)
         ctrl = event.state & MOD_MASK
 
         if key is KeyboardKey.DELETE:
@@ -329,12 +328,11 @@ class SatellitesTool(Gtk.Box):
             view.do_unselect_all(view)
 
     def on_tr_key_press(self, view, event):
-        """ Handling  transponder view keystrokes. """
-        key_code = event.hardware_keycode
-        if not KeyboardKey.value_exist(key_code):
+        """ Handling transponder view keystrokes. """
+        key = KeyboardKey(event.hardware_keycode)
+        if key is KeyboardKey.UNDEFINED:
             return
 
-        key = KeyboardKey(key_code)
         ctrl = event.state & MOD_MASK
 
         if key is KeyboardKey.DELETE: