Don't run timers after shutdown is called--crashes when a window is closd or fullscreen toggled

ToolJobs.h

@@ -18,6 +18,7 @@
     NSMutableArray *names_;
     NSMutableArray *pids_;
     BOOL hasSelection;
+    BOOL shutdown_;
 }
 @property (nonatomic, assign) BOOL hasSelection;

ToolJobs.m

@@ -174,6 +174,7 @@ static const CGFloat kMargin = 4;
 - (void)shutdown
 {
     [[NSNotificationCenter defaultCenter] removeObserver:self];
+    shutdown_ = YES;
     [timer_ invalidate];
     [kill_ unbind:@"enabled"];
     timer_ = nil;
@@ -181,6 +182,9 @@ static const CGFloat kMargin = 4;
 - (void)updateTimer:(id)sender
 {
+    if (shutdown_) {
+        return;
+    }
     ToolWrapper *wrapper = (ToolWrapper *)[[self superview] superview];
     pid_t rootPid = [[[wrapper.term currentSession] SHELL] pid];
     NSSet *pids = [[ProcessCache sharedInstance] childrenOfPid:rootPid levelsToSkip:0];
@@ -208,8 +212,10 @@ static const CGFloat kMargin = 4;
 - (void)fixCursor
 {
-    ToolWrapper *wrapper = (ToolWrapper *)[[self superview] superview];
-	[[[wrapper.term currentSession] TEXTVIEW] updateCursor:[[NSApplication sharedApplication] currentEvent]];
+    if (!shutdown_) {
+        ToolWrapper *wrapper = (ToolWrapper *)[[self superview] superview];
+        [[[wrapper.term currentSession] TEXTVIEW] updateCursor:[[NSApplication sharedApplication] currentEvent]];
+    }
 }
 - (BOOL)isFlipped