Interestingly we are working on similar patterns this week, the design we are recommending has a clear classification of error messages.
- Classification based on type : Error, Warning, Info
- Classification based on target : which part of the screen is initiating the message.
The first classification is used to decide on the color and fading properties.
The second one is a little trickier.
Our application can be used in widescreen monitors, it makes sure the message is shown in close proximity to what initiates the action. Our application has clear demarcation of screen element like I have shown in the image.
There is a easy contextual link between the message and from where it has popped. This is mostly applicable on feedback actions which are specifically triggered when user performs an action and is waiting for something from the system.
If this user action affects an entire system, we also have a provision to show the messages clearly across the whole page. This remains at the center and wraps around the content.
The idea is to fade this notification after a specified timeout (based on message severity), and also give user an option to close it from the icon (optionally on ESC key). If user chooses to click on the bubble then we expand the notification and wait for user's explicit close action.
It is highly relevant when users get feedback near to the area where s/he is focusing. It helps in maintaining the visual context.
Our screens have huge amount of fields and data as it is an enterprise application. Hence we also make sure that we are keeping the message boxes as overlays, so the entire UI does not shift. (Believe me, downwards shift of entire UI annoys the users if it is not smoothly done).
My use case may not directly apply to yours but I hope I have been of some help.