Fixed: if a CPAlert message was 3 lines or more and there was no informative text, the upper half of the CPAlert buttons would not react to clicks as the blank informative label partially covered them.

AppKit/CPAlert.j

@@ -365,6 +365,8 @@ CPCriticalAlertStyle        = 2;
 
     [_messageLabel setFrame:CGRectMake(inset.left, inset.top, textWidth, messageSize.height + sizeWithFontCorrection)];
     [_informativeLabel setFrame:CGRectMake(inset.left, CGRectGetMaxY([_messageLabel frame]) + informativeOffset, textWidth, informativeSize.height + sizeWithFontCorrection)];
+    // Don't let an empty informative label partially cover the buttons.
+    [_informativeLabel setHidden:!informationString];
 
     var aRepresentativeButton = _buttons[0],
         buttonY = MAX(CGRectGetMaxY([_alertImageView frame]), CGRectGetMaxY(informationString ? [_informativeLabel frame] : [_messageLabel frame])) + buttonOffset; // the lower of the bottom of the text and the bottom of the icon.

Tests/Manual/CPAlertTest/AppController.j

@@ -25,7 +25,10 @@
          "Theorise", "Cancel"],
         [@"Snakes. Why did it have to be snakes?",
          nil,
-         "Torch", "Cancel"]
+         "Torch", "Cancel"],
+         [@"Sometimes a message can be really long and just appear to go on and on. It could be a speech. It could be the television.",
+          nil,
+          "Off", "Cancel"]
     ];
     messageIndex = 0;
 
@@ -69,12 +72,11 @@
     if (![variations count])
         return;
 
-
     var variation = variations[0],
         message = messages[messageIndex],
         alert = [[CPAlert alloc] init];
 
-    messageIndex = 1 - messageIndex;
+    messageIndex = (messageIndex + 1) % messages.length;
     [variations removeObjectAtIndex:0];
 
     [alert setDelegate:self];