Minor fix to apple+arrow keys on OS X.

src/window.cc

@@ -230,24 +230,16 @@ bool Window::on_key_press_event(GdkEventKey *event) {
       event->hardware_keycode=119;
     }
     else if(event->keyval==GDK_KEY_Up) {
-      if(auto text_view=dynamic_cast<Gtk::TextView*>(get_focus())) {
-        if(event->state & GDK_SHIFT_MASK)
-          text_view->get_buffer()->select_range(text_view->get_buffer()->begin(), text_view->get_buffer()->get_insert()->get_iter());
-        else
-          text_view->get_buffer()->place_cursor(text_view->get_buffer()->begin());
-        text_view->scroll_to(text_view->get_buffer()->get_insert());
-      }
-      return true;
+      event->keyval=GDK_KEY_Home;
+      event->state=event->state & GDK_SHIFT_MASK;
+      event->state+=GDK_CONTROL_MASK;
+      event->hardware_keycode=115;
     }
     else if(event->keyval==GDK_KEY_Down) {
-      if(auto text_view=dynamic_cast<Gtk::TextView*>(get_focus())) {
-        if(event->state & GDK_SHIFT_MASK)
-          text_view->get_buffer()->select_range(text_view->get_buffer()->end(), text_view->get_buffer()->get_insert()->get_iter());
-        else
-          text_view->get_buffer()->place_cursor(text_view->get_buffer()->end());
-        text_view->scroll_to(text_view->get_buffer()->get_insert());
-      }
-      return true;
+      event->keyval=GDK_KEY_End;
+      event->state=event->state & GDK_SHIFT_MASK;
+      event->state+=GDK_CONTROL_MASK;
+      event->hardware_keycode=119;
     }
   }
 #endif