[gnome-mahjongg] Set button release event mask on GameView

[Carlos Garnacho <carlosg src gnome org>]

commit 375d9801b138fdc66cb5c1b66152e02c2c4bc927
Author: Carlos Garnacho <carlosg gnome org>
Date:   Thu Sep 10 15:52:22 2015 +0200

    Set button release event mask on GameView
    
    This is needed to ensure a meaningful event propagation across
    the parents of GameView. Otherwise the window dragging gesture
    will be left in an inconsistent state, and stuck for the next
    time as the button release event won't be received.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=754837

 src/game-view.vala |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/game-view.vala b/src/game-view.vala
index 3d738d0..c04802b 100644
--- a/src/game-view.vala
+++ b/src/game-view.vala
@@ -45,7 +45,7 @@ public class GameView : Gtk.DrawingArea
     public GameView ()
     {
         can_focus = true;
-        add_events (Gdk.EventMask.BUTTON_PRESS_MASK);
+        add_events (Gdk.EventMask.BUTTON_PRESS_MASK | Gdk.EventMask.BUTTON_RELEASE_MASK);
     }
 
     public void set_background (string? colour)