EditWindowController.m

- (void)startObserving
{
	// start observing the entriesController's selection property,
	// so we can properly update the third pane with a populated
	// entry view once an entry is selected
	[entriesController addObserver:self 
					  forKeyPath:@"selection" 
						 options:NSKeyValueObservingOptionNew 
						 context:EntryWindowContext];
}

- (void)stopObserving
{
	[entriesController removeObserver:self forKeyPath:@"selection"];
}

- (void)observeValueForKeyPath:(NSString *)keyPath 
					  ofObject:(id)object 
						change:(NSDictionary *)change 
					   context:(void *)context
{
	//DLog(@"got a change in %@ to %@", keyPath, [object valueForKey:keyPath]);
	if (context == EntryWindowContext)
	{
		if ([keyPath isEqual:@"selection"])
		{
			DLog(@"selection changed...");
			id selectedEntry = [object valueForKey:@"selection"];
			DLog(@"selection: %@", selectedEntry);
			
			if (selectedEntry != nil && [selectedEntry isKindOfClass:[Entry class]]) {
				DLog(@"presenting entry view");
				[self showEntryView];
			} else {
				DLog(@"showing no selection view");
				[self showNoSelectionView];
			}
		}
	}
}

- (void)showNoSelectionView 
{
	// make sure that entry view itself is not the current subview, by removing it
	[entryView removeFromSuperview];
	// add our no-selection view as the subview to the entry display pane
	[entryViewPane addSubview:noEntryView];
	// set the frame of the new view to match the parent, in case it's changed
	[noEntryView setFrame:[entryViewPane bounds]];
}

- (void)showEntryView
{
	[noEntryView removeFromSuperview];
	[entryViewPane addSubview:entryView];
	[entryView setFrame:[entryViewPane bounds]];
}