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@@ -132,7 +132,7 @@
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      (- (id) hitTest:(NSPoint) aPoint is
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         (if (PointInRect aPoint (self frame)) 
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             (then self)
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-            (else NULL))) ;; in the most hard-won conclusion of this project, this should be NULL and not nil.
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+            (else nil))) ;; in the most hard-won conclusion of this project, this should be NULL and not nil.
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      (- (BOOL) shouldDelayWindowOrderingForEvent:(id) theEvent is YES)
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@@ -140,7 +140,7 @@
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      (- (int) draggingSourceOperationMaskForLocal:(BOOL) flag is NSDragOperationCopy)
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-     (- (id) menuForEvent:(id) e is NULL)
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+     (- (id) menuForEvent:(id) e is nil)
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      (- (void) mouseDown:(id) e is
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         (NSApp preventWindowOrdering)
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@@ -152,7 +152,7 @@
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         ;; Is this a significant distance from the mouseDown?
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         (unless (< (distanceSquaredBetweenPoints start current) 52.0)              
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-                (set dragStart (self convertPoint:start fromView:NULL))
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+                (set dragStart (self convertPoint:start fromView:nil))
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                 (set imageSize ($dragImage size))
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                 (set dragStart (list (- (dragStart first) (/ (imageSize first) 3.0))
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                                      (- (dragStart second) (/ (imageSize second) 3.0))))
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@@ -199,7 +199,7 @@
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         (unless (eq pi oldInfo)
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                 ((@undoManager prepareWithInvocationTarget:self) replacePageInfoAt:i withPageInfo:oldInfo)
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                 (@pageInfos replaceObjectAtIndex:i withObject:pi)
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-                ((NSNotificationCenter defaultCenter) postNotificationName:"PackModelChangedNotification" object:self userInfo:NULL)))
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+                ((NSNotificationCenter defaultCenter) postNotificationName:"PackModelChangedNotification" object:self userInfo:nil)))
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      (- (void) setImageRep:(id) r pageOfRep:(int) repPage forPage:(int) viewPage is
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         (set pi ((PageInfo alloc) init))
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@@ -266,7 +266,7 @@
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             (then
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                  (set str (NSString stringWithContentsOfFile:currentPath
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                                encoding:NSUTF8StringEncoding
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-                               error:NULL))
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+                               error:nil))
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                  (if str
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                      (then
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                           (set atts (self textAttributes))              
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@@ -609,7 +609,7 @@
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                       page)))
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      (- (int) pageForPointInWindow:(NSPoint) p is
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-        (set x (self convertPoint:p fromView:NULL))
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+        (set x (self convertPoint:p fromView:nil))
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         (self pageForPoint:x))
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      (- (int) draggingEntered:(id) sender is