[gcompris] play_piano, fixed the <Delete> key

[Bruno Coudoin <bcoudoin src gnome org>]

commit 6920e8faa24ac604a5fab77b032c9aba0bd1e346
Author: Bruno Coudoin <bruno coudoin free fr>
Date:   Tue Oct 16 03:25:57 2012 +0200

    play_piano, fixed the <Delete> key
    
    Now the <Delete> key erases all the notes as documented.

 .../piano_composition.py                           |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/piano_composition-activity/piano_composition.py b/src/piano_composition-activity/piano_composition.py
index a897400..ce7f675 100644
--- a/src/piano_composition-activity/piano_composition.py
+++ b/src/piano_composition-activity/piano_composition.py
@@ -649,7 +649,7 @@ dialogue to\nenable the sound."), None)
     def updateToWhole(self, unused1, unused2, unused3):
         self.staff.updateToWhole()
 
-    def askAndEraseStaff(self, unused1, unused2, unused3):
+    def askAndEraseStaff(self, unused1=None, unused2=None, unused3=None):
         # @FIXME, should have a dialog asking for confirmation
         self.staff.eraseAllNotes()