dock.extra: Could not connect the action buttonPressed ???

What does this log mean ?

11-08-14 7:44:30.283 PM com.apple.dock.extra: Could not connect the action buttonPressed: to target of class NSApplication

11-08-14 7:44:30.284 PM com.apple.dock.extra: Could not connect the action buttonPressed: to target of class NSApplication

11-08-14 7:44:30.285 PM com.apple.dock.extra: Could not connect the action buttonPressed: to target of class NSApplication

11-08-14 7:44:30.286 PM com.apple.dock.extra: Could not connect the action buttonPressed: to target of class NSApplication

11-08-14 7:44:30.285 PM com.apple.dock.extra: 2011-08-14 19:44:30.281 com.apple.dock.extra[272:1707] Could not connect the action buttonPressed: to target of class NSApplication

11-08-14 7:44:30.285 PM com.apple.dock.extra: 2011-08-14 19:44:30.283 com.apple.dock.extra[272:1707] Could not connect the action buttonPressed: to target of class NSApplication

11-08-14 7:44:30.286 PM com.apple.dock.extra: 2011-08-14 19:44:30.284 com.apple.dock.extra[272:1707] Could not connect the action buttonPressed: to target of class NSApplication

11-08-14 7:44:30.287 PM com.apple.dock.extra: 2011-08-14 19:44:30.285 com.apple.dock.extra[272:1707] Could not connect the action buttonPressed: to target of class NSApplication

11-08-14 7:48:19.077 PM com.apple.dock.extra: Could not connect the action buttonPressed: to target of class NSApplication