Fix incorrect and messy Key action code for handling unknown keys

The Key action now supports typing strings on Windows that do not
match an existing key name, if hardware events are not required.
Such strings will always be typed using the Unicode keyboard.

The Windows-specific code in this class has also been reduced a bit.

dragonfly/actions/action_key.py

@@ -413,50 +413,31 @@ def _parse_single(self, spec, hardware_events_required):
         error_message = ("Keyboard interface cannot type this character: %r"
                          % keyname)
         code = typeables.get(keyname)
-        is_windows = sys.platform.startswith("win")
-        if code is None and not is_windows:
-            # Delegate to the keyboard class. Any invalid keys will cause
-            # error messages later than normal, but this allows using valid
-            # key symbols that dragonfly doesn't define.
-            code = self._keyboard.get_typeable(keyname)
-            typeables[keyname] = code
-
-        elif code is None and is_windows:
-            # Handle this differently on Windows.
-            invalid_key_name = (
-                len(keyname) > 1 and
-
-                # Check if 'keyname' is an encoded character or code point.
-                (keyname.encode('unicode-escape', errors='ignore')
-                 .startswith(b"\\\\"))
-            )
-            if invalid_key_name:
-                # Raise an error on Windows for unknown keys that aren't
-                # single characters, encoded characters or Unicode code
-                # points.
-                raise ActionError("Invalid key name: %r" % keyname)
-
-            # Otherwise get a new Typeable.
+        if code is None:
+            # Delegate to the platform keyboard class. Any invalid keys will
+            # cause error messages later than normal, but this allows using
+            # valid key symbols that dragonfly doesn't define.
             try:
                 code = self._keyboard.get_typeable(keyname)
+                typeables[keyname] = code
             except ValueError:
                 if hardware_events_required:
                     # Return an error message to display when this action
                     # is executed.
                     return [], error_message
 
-                # Use the Unicode keyboard instead.
-                try:
-                    code = self._keyboard.get_typeable(keyname,
-                                                       is_text=True)
-                except ValueError:
-                    return [], error_message
-
-            # Save the typeable.
-            typeables[keyname] = code
+                # If on Windows and if hardware events are not required,
+                # then attempt to use the Unicode keyboard instead.
+                if sys.platform.startswith("win"):
+                    try:
+                        code = self._keyboard.get_typeable(keyname,
+                                                           is_text=True)
+                        typeables[keyname] = code
+                    except ValueError:
+                        return [], error_message
         else:
             # Update the Typeable. Return an error message if this fails.
-            # Note: this only does anything on Windows.
+            # Note: this only currently does anything on Windows.
             if not code.update(hardware_events_required):
                 return [], error_message