Fix for endless loop with default buttons.

AppKit/CPButton.j

@@ -569,6 +569,7 @@ CPButtonStateMixed  = CPThemeState("mixed");
 */
 - (void)setKeyEquivalent:(CPString)aString
 {
+    _keyEquivalent = aString || @"";
     // Check if the key equivalent is the enter key
     // Treat \r and \n as the same key equivalent. See issue #710.
     if (aString === CPNewlineCharacter || aString === CPCarriageReturnCharacter)
@@ -581,8 +582,6 @@ CPButtonStateMixed  = CPThemeState("mixed");
         [[self window] setDefaultButton:nil];
         [self setDefaultButton:NO];
     }
-
-    _keyEquivalent = aString || @"";
 }
 
 - (void)viewWillMoveToWindow:(CPWindow)aWindow

AppKit/CPWindow/CPWindow.j

@@ -2411,7 +2411,8 @@ CPTexturedBackgroundWindowMask
 
     _defaultButton = aButton;
 
-    [_defaultButton setKeyEquivalent:CPCarriageReturnCharacter];
+    if ([_defaultButton keyEquivalent] !== CPCarriageReturnCharacter)
+        [_defaultButton setKeyEquivalent:CPCarriageReturnCharacter];
 }
 
 - (CPButton)defaultButton