[mutter] backend: Reset current device id when current device removed

[Jonas Ådahl <jadahl src gnome org>]

commit 3ee1999c70910f6349b15ed5df0b7d7965f6f5e7
Author: Benoit Gschwind <gschwind gnu-log net>
Date:   Wed Oct 25 22:13:30 2017 +0200

    backend: Reset current device id when current device removed
    
    Bluetooth mouse usually goes in sleep state after a timeout, when that
    happen the mouse is disconnected and on_device_removed function is
    called. Before the patch if a touch device is available the
    on_device_removed function hide the cursor. The issue is that the cursor
    does not reappear once the bluetooth mouse is reconnected because
    MetaBackend::current_device_id is not invalidated when on_device_removed
    was called.
    
    The patch set MetaBackend::current_device_id to 0 if the current device
    is removed. This will make update_last_device to be triggered as soon as
    another input device is used or the bluetooth mouse reconnect, as
    consequence that the cursor reappear. The id 0 is never given to devices
    and can safely used as undefine id.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=761067

 src/backends/meta-backend.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/src/backends/meta-backend.c b/src/backends/meta-backend.c
index 9083a43..4ebceb4 100644
--- a/src/backends/meta-backend.c
+++ b/src/backends/meta-backend.c
@@ -337,6 +337,8 @@ on_device_removed (ClutterDeviceManager *device_manager,
       gboolean has_touchscreen, has_pointing_device;
       ClutterInputDeviceType device_type;
 
+      priv->current_device_id = 0;
+
       device_type = clutter_input_device_get_device_type (device);
       has_touchscreen = check_has_slave_touchscreen (device_manager);