Getting keyboard type: carbon vs CG

Hi All,

I am trying to wean one of my Cocoa applications of it's last Carbon dependency. In this specific case I need to tell keyboard events from different keyboards apart.

Ideally I could figure out which USB device a keyboard event came from, but that doesn't seem to be within the scope of a Cocoa app.

I settled for the next best thing, which was using the keyboard type.

So I replaced carbon based code (GetEventParameter, kEventParamKeyboardType) with CoreGraphics (CGEventSourceGetKeyboardType).

Problem is the CoreGraphics alternative does not appear to return the correct code. The code is (drop into NSApplication subclass):

- (void)sendEvent:(NSEvent *)anEvent {
	
	NSEventType	type=[anEvent type];
	
	if(type==NSKeyDown || type==NSKeyUp)
	{
		EventRef	ce=(EventRef)[anEvent eventRef];
		
		if(ce)
		{
			unsigned	kbt;
			
			GetEventParameter(
				ce,
				kEventParamKeyboardType,
				typeUInt32, NULL,
				sizeof kbt,
				NULL,
				&kbt
			);
			NSLog(@"kbt (carbon): %d",kbt);
		}
		
		CGEventSourceRef	evSrc=CGEventCreateSourceFromEvent([anEvent CGEvent]);
		
		if(evSrc)
		{
			unsigned	kbt=(NSUInteger)CGEventSourceGetKeyboardType(evSrc);
			
			CFRelease(evSrc);
			
			NSLog(@"kbt (cg): %d",kbt);
		}
	}
	
	[super sendEvent:anEvent];
}

The output for keyboard 1 is:

2009-12-20 13:21:00.827 Anneal[75832:60f] kbt (carbon): 46
2009-12-20 13:21:00.829 Anneal[75832:60f] kbt (cg): 46

And for keyboard 2:

2009-12-20 13:21:04.373 Anneal[75832:60f] kbt (carbon): 204
2009-12-20 13:21:04.374 Anneal[75832:60f] kbt (cg): 46


Any thoughts? Is this a bug in CGEventSourceGetKeyboardType?

Thanks

Gerd