[gnome-sudoku] Fix dragging the window after clicking the game view

[Michael Catanzaro <mcatanzaro src gnome org>]

commit bb078ec242ce412a741b3f56ecd439813124c884
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Fri Sep 11 12:32:16 2015 -0500

    Fix dragging the window after clicking the game view
    
    https://bugzilla.gnome.org/show_bug.cgi?id=754837

 src/sudoku-view.vala |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/sudoku-view.vala b/src/sudoku-view.vala
index a8059df..afc837a 100644
--- a/src/sudoku-view.vala
+++ b/src/sudoku-view.vala
@@ -115,7 +115,7 @@ private class SudokuCellView : Gtk.DrawingArea
         // background_color is set in the SudokuView, as it manages the color of the cells
 
         can_focus = true;
-        events = EventMask.EXPOSURE_MASK | EventMask.BUTTON_PRESS_MASK | EventMask.KEY_PRESS_MASK;
+        events = EventMask.EXPOSURE_MASK | EventMask.BUTTON_PRESS_MASK | EventMask.BUTTON_RELEASE_MASK | 
EventMask.KEY_PRESS_MASK;
 
         if (is_fixed && game.mode == GameMode.PLAY)
             return;