got rid of the interval polling architecture, also displaying mouse keycodes in the status bar

data/key-mapper.glade

@@ -266,7 +266,7 @@
     <property name="title" translatable="yes">Key Mapper</property>
     <property name="icon_name">mouse</property>
     <signal name="delete-event" handler="on_close" swapped="no"/>
-    <signal name="key-press-event" handler="on_window_key_press_event" swapped="no"/>
+    <signal name="event" handler="on_window_event" swapped="no"/>
     <child>
       <object class="GtkBox" id="wrapper">
         <property name="visible">True</property>

keymapper/gtk/row.py

@@ -59,23 +59,10 @@ class Row(Gtk.ListBoxRow):
         character = self.character_input.get_text()
         return character if character else None
 
-    def start_watching_keycodes(self, *args):
-        """Start to periodically check if a keycode has been pressed.
-
-        This also includes e.g. middle mouse buttons, as opposed to
-        get_keycode from gdk events.
-        """
-        keycode_reader.clear()
-
-        def iterate():
-            self.check_newest_keycode()
-            return self.keycode.is_focus() and self.window.window.is_active()
-
-        GLib.timeout_add(1000 / 30, iterate)
-
-    def check_newest_keycode(self):
+    def set_new_keycode(self, new_keycode):
         """Check if a keycode has been pressed and if so, display it."""
-        new_keycode = keycode_reader.read()
+        # the newest_keycode is populated since the ui regularly polls it
+        # in order to display it in the status bar.
         previous_keycode = self.get_keycode()
         character = self.get_character()
 
@@ -108,7 +95,7 @@ class Row(Gtk.ListBoxRow):
             return
 
         # else, the keycode has changed, the character is set, all good
-        custom_mapping.change(previous_keycode, new_keycode, character)
+        custom_mapping.change(new_keycode, character, previous_keycode)
 
     def highlight(self):
         """Mark this row as changed."""
@@ -150,12 +137,6 @@ class Row(Gtk.ListBoxRow):
         if keycode is not None:
             keycode_input.set_label(str(keycode))
 
-        # to capture regular keyboard keys or extra-mouse keys
-        keycode_input.connect(
-            'focus-in-event',
-            self.start_watching_keycodes
-        )
-
         # make the togglebutton go back to its normal state when doing
         # something else in the UI
         keycode_input.connect(

keymapper/gtk/window.py

@@ -193,12 +193,30 @@ class Window:
         key_list = self.get('key_list')
         key_list.forall(lambda row: row.unhighlight())
 
-    def on_window_key_press_event(self, window, event):
-        """Write down the pressed key on the UI.
+    def on_window_event(self, button, event):
+        """Write down the pressed key in the UI.
 
-        Helps to understand what the numbers in the mapping are about.
+        Works with any mouse and keyboard event.
         """
-        self.get('keycode').set_text(str(event.get_keycode()[1]))
+        # to capture regular keyboard keys or extra-mouse keys
+        keycode = keycode_reader.read()
+
+        if keycode is None:
+            return
+
+        if keycode == 280:
+            # disable mapping the left mouse button because it would break
+            # the mouse. Also it is emitted right when focusing the row
+            # which breaks the current workflow.
+            return
+
+        self.get('keycode').set_text(str(keycode))
+
+        # inform the currently selected row about the new keycode
+        focused = self.window.get_focus()
+        row = focused.get_parent().get_parent()
+        if isinstance(focused, Gtk.ToggleButton) and isinstance(row, Row):
+            row.set_new_keycode(keycode)
 
     def on_apply_system_layout_clicked(self, button):
         """Load the mapping."""
@@ -292,6 +310,7 @@ class Window:
 
         try:
             new_preset = get_available_preset_name(self.selected_device)
+            custom_mapping.empty()
             custom_mapping.save(self.selected_device, new_preset)
             self.get('preset_selection').append(new_preset, new_preset)
             self.get('preset_selection').set_active_id(new_preset)

keymapper/reader.py

@@ -66,7 +66,7 @@ class KeycodeReader:
         ]
 
     def read(self):
-        """Get the newest key or None if none was pressed."""
+        """Get the newest keycode or None if none was pressed."""
         newest_keycode = None
         for virtual_device in self.virtual_devices:
             while True:

tests/testcases/integration.py

@@ -128,8 +128,7 @@ class Integration(unittest.TestCase):
                 Event(evdev.events.EV_KEY, keycode - 8, 1)
             ]
 
-            time.sleep(0.1)
-            gtk_iteration()
+            self.window.on_window_event(None, None)
 
             self.assertEqual(int(row.keycode.get_label()), keycode)