BUG: Potential bug: don't assume non-positive values of NSTrackingRectTag are invalid.

Author: dgobbi

Rendering/vtkCocoaGLView.h

@@ -59,6 +59,7 @@
   @private
   vtkCocoaRenderWindowRef myVTKRenderWindow;
   NSTrackingRectTag rolloverTrackingRectTag;
+  BOOL rolloverTrackingRectSet;
 }
 
 - (vtkCocoaRenderWindowRef)getVTKRenderWindow;

Rendering/vtkCocoaGLView.mm

@@ -35,6 +35,9 @@ - (id)initWithFrame:(NSRect)frameRect
   self = [super initWithFrame:frameRect];
   if (self)
     {
+    // The tracking rect is not set yet.
+    rolloverTrackingRectSet = NO;
+
     // Force Cocoa into "multi threaded mode" because VTK spawns pthreads.
     // Apple's docs say: "If you intend to use Cocoa calls, you must force
     // Cocoa into its multithreaded mode before detaching any POSIX threads.
@@ -92,10 +95,10 @@ - (void)drawRect:(NSRect)theRect
 - (void)clearTrackingRect
 {
   // remove any tracking rect we have
-  if (rolloverTrackingRectTag > 0)
+  if (rolloverTrackingRectSet)
     {
     [self removeTrackingRect:rolloverTrackingRectTag];
-    rolloverTrackingRectTag=0;
+    rolloverTrackingRectSet = NO;
     }
 }
 
@@ -110,6 +113,7 @@ - (void)resetTrackingRect
                                             owner:self
                                          userData:NULL
                                      assumeInside:NO];
+  rolloverTrackingRectSet = YES;
 }
 
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