make headerbar autohidding toggeable

data/de.wolfvollprecht.UberWriter.gschema.xml

@@ -21,6 +21,13 @@
         It can cause performance problems to some users
       </description>
     </key>
+    <key name='poll-motion' type='b'>
+      <default>true</default>
+      <summary>Allow Uberwriter to poll cursor motion</summary>
+      <description>
+        Used for hidding the headerbar after 3 seconds if the cursor is not moving.
+      </description>
+    </key>
     <key name='open-file-path' type='s'>
       <default>"/tmp"</default>
       <summary>Open file base path</summary>

uberwriter/UberwriterWindow.py

@@ -104,8 +104,10 @@ class UberwriterWindow(Gtk.ApplicationWindow):
         self.status_bar_visible = True
         self.was_motion = True
         self.buffer_modified_for_status_bar = False
-        self.connect("motion-notify-event", self.on_motion_notify)
-        GObject.timeout_add(3000, self.poll_for_motion)
+
+        if self.settings.get_value("poll-motion"):
+            self.connect("motion-notify-event", self.on_motion_notify)
+            GObject.timeout_add(3000, self.poll_for_motion)
 
         self.accel_group = Gtk.AccelGroup()
         self.add_accel_group(self.accel_group)