[gnome-shell] st-button: Handle touch-cancel events

[Carlos Garnacho <carlosg src gnome org>]

commit 99ce3deeb05162c0e97a884f47858e66930c8c0b
Author: verdre <verdre v0yd nl>
Date:   Fri Jan 18 09:37:04 2019 +0100

    st-button: Handle touch-cancel events
    
    Handling those events is neccessary if a touch event that pressed down a
    button turns out to be a gesture. In this case the button should be
    released without emitting the clicked signal.

 src/st/st-button.c | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/src/st/st-button.c b/src/st/st-button.c
index a3a7b2442..a95ddff2d 100644
--- a/src/st/st-button.c
+++ b/src/st/st-button.c
@@ -262,6 +262,10 @@ st_button_touch_event (ClutterActor      *actor,
       clutter_input_device_sequence_ungrab (device, sequence);
       return CLUTTER_EVENT_STOP;
     }
+  else if (event->type == CLUTTER_TOUCH_CANCEL)
+    {
+      st_button_fake_release (button);
+    }
 
   return CLUTTER_EVENT_PROPAGATE;
 }