I'm working on a desktop notification system and is pondering some issues I haven't seen much discussion about , perhaps the list has some insights and thoughts on the subject :)
Placement -- Usually desktop notifications display in the lower right corner, typically because they "originate" from the taskbar tray. If you discount this tradition is the right-lower corner really the best choice? It seems placement should partly be a factor of the notification priority. "Casual" notifications should probably be displayed somewhere on the edge of the screen in order to not be too obtrusive.
Aren't "Important" notifications best placed in the center of the screen though so that they arent missed? Or perhaps a better method would be to make them "sticky", ie you have to manually dismiss them. Otherwise you might miss an important notification while looking at something else or being away from the computer (although that could be detected) It would seem an alternative for the lower-right corner for "casual" notifications would be on the right edge but in the middle of the screen
Animation and multiple notifications --- Typically when multiple notification trigger they stack on top of each other, but I've always found it a bit annoying to have a bunch of notifications appear at once and dissappearing before having time to read them all. Then again,displaying them in sequence doesn't seem like such a good idea either. Perhaps rather than animating each notification separely they should be displayed in bundles. Ie i queue all "casual" notifications received during a minute or so and display them in one notification instead of several. "Critical" notifications should probably be displayed immediately and separately however.
If placement is in the right-middle screen an appropriate animation might be to have it slide out from the right edge instead of just fading in, too obtrusive?
General use -- In general it seems notifications can be a really really bad thing, receiving "casual" alerts every time something is updated would severely hamper flow. Two ways to possible counteract this would be to provide a notification backlog that could be shown when you desire instead of when they're triggered. Another nice functuality would perhaps to have a "flow" mode during which all notifications cease and when reactivated shows the backlog.
It does however feel like there's the opportunity make notifications ever smarter somehow but I can't put my finger on it...