Method parameter is sometimes zeroed (weird problem)

FROM : Stuart Crook
DATE : Mon Nov 19 17:58:25 2007

Hi, I'm having a really weird problem, which is probably something 
obvious...

ObjectA is a subclass of NSObject and implements the method (void)
tabView:(NSTabView *)tabview didChangeHeightBy:(float)change, which 
is a delegate method (of my own creation, not Cocoa's) for ObjectB.

ObjectB is a subclass of NSTabView, which holds ObjectA as its 
delegate and invokes the delegate method on it with [[self delegate] 
tabView: self didChangeHeightBy: change] where 'change' is a float 
value.

The problem is that in the delegate method, the 'change' parameter is 
always 0.0. I've put in NSLogs, traced the values in debug and passed 
in constant float values, and while a non-zero value is always 
passed, the received parameter 'change' is always 0.0. BUT only when 
called in this way. If I get ObjectA to call the method on itself, 
the change parameter is passed correctly. The same is true if I call 
the method from ObjectC, another NSObject subclass.

This is under 10.4.11 on Intel. All objects are compiled from source 
inside the same project.