MacOS – Where’d My iTunes Today Widget Go

I'm a Mac OS X developer and I just finished adding Notification Center support to my app. For what it's worth, here's what I found out:

• By default, notifications (the alerts) are NOT shown if the application is already frontmost (this explains why alerts refuse to show up sometimes, and you only see the notification in Notification Center). This is up to given applications to overwrite and it is not very straightforward, so do expect most applications to not show notifications when they're active. In my opinion, this is very annoying.
• The application, after sending a notification still has a lot of control over that given notification. It can remove it from your screen at any time it wants, regardless of the settings you have. Basically, if Safari, for some reason was set to remove notifications after X seconds, it will do that, your settings do not matter.

I have no idea if this is a bug in Safari or Notification Center, or both. However, I am fairly confident that there is nothing you can do about the second issue (there might be a hidden defaults setting for the first one, but I haven't heard of it). I did check the WebKit API Specification, to make sure it's not something that the individual websites are doing, and you can rule out websites from your suspect's list, because they do not have any control over the notifications.

I guess we'll have to wait and see if Apple will address this in its next bug fix release (10.9). However, by the looks of it, not showing notifications when the app is frontmost is a "feature", so don't get your hopes up.

I was having the exact same problem, and I think it started after installing an app which included a Today widget. I've finally fixed it by trying a few things, so I'm not sure what actually solved the problem. I suggest you try these things in the same order:

1. Open the Terminal (/Applications/Utilities/Terminal.app) and paste the following lines there, then hit [Enter].

   /System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/\
   LaunchServices.framework/Versions/A/Support/lsregister -kill -r -domain local\
   -domain system -domain user -seed
   

   This will rebuild the app cache, which includes all extensions.

2. A few extensions will probably be missing now (in the Extensions preference pane). That is no big deal; just quit and open all apps that come with extensions. Logging out and back in would do the trick too.

3. Go to System Preferences > Extensions > Today, and reorder the items to your liking. Make sure you keep all checked items together and move them to the top of the list! I suspect the Today view could get confused when enabled widgets are mixed with disabled ones.

4. Log out and back in and see if the widget order is correct.

Hopefully, this approach works for you too.