Audience / Scenario
The people who visit/use the site:
- want to be alerted to important breaking news without having to search for it - so it has to be prominent
The people who own the site:
- want to display ad-hoc breaking news alert on the home page as quickly as possible yet don't want to make it look a mess
When and where?
You should use this pattern when:
- your home page contains a complex layout, highly customised graphical design or anything else which would delay the addition of the news
- you want maximum freedom as to what is displayed (e.g. you want to show picutres or custom formatting, etc., rather than just the title of the news)
- you want the item to remain visible until it's removed rather than have it automatically hidden because newer items have been added
You should avoid this pattern if:
- you want more recent items to automatically supercede the news alert
- you want all news to have the same prominence
You should incoporate this pattern in any of the following locations:
- the site home page
- key entry pages within the site
- a page that has complex layout and/or design and requires easy ad-hoc prominent display of a custom message
Solution
Create a trigger page within your site - when the page exists, the contents of it are shown in a news alert panel, when it doesn't exist the news alert panel disappears.
A pre-defined panel or section of your home page will be used to show the news alert, thus allowing the layout and design of that panel to be seamlessly integrated with the rest of the page.
When you add the news alert page, the home page panel is automatically shown with the contents of the news alert page.
Why?
Many organisations have an occasional need to show breaking news or some other special event on their home page in a visually distinct manner and location to the general news headlines shown elsewhere.
By using a specific page to store the news alert, you get much more design freedom - you can choose whether or not to include images, text formatting, etc., at the time of adding the news. In addition, you don't have to worry (too much) about making your news alert fit in with the home page design.
The panel on the home page will be pre-designed to merge the surrounding home page with the news alert so that the overall design is consistent.
If you were to edit the home page itself to add in the news alert, you'd run in to all kinds of extra tasks because you'd have to deal with the usually more complex layout and design found on the home page.
Example
We've used this on a number of intranets but, due to intranets being generally private, we can't show you them 
Added by
Setting up a predefined panel in a complex layout is straight forward. What macro would be used to conditionally show or hide this panel based on the presence of another page?
The [builder-show macro]
Simply configure it to show it's contents when a specific page exists. Within the contents, use the include macro to pull in the contents of that page to the panel.