Remove oberserver from jobs tool to avoid a crash

ToolJobs.m

@@ -151,6 +151,7 @@ static const int kMaxJobs = 20;
 - (void)dealloc
 {
+    [[NSNotificationCenter defaultCenter] removeObserver:self];
     [signal_ release];
     [tableView_ release];
     [scrollView_ release];
@@ -233,4 +234,4 @@ static const int kMaxJobs = 20;
     kill(p, [[signal_ selectedItem] tag]);
 }
-@end
+@end
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