In ubuntu, the notification popup that occurs in the upper right is unobtrusive, and when you mouse over it, it will dim so that you can see behind it and it will allow you to click on things that are behind it. In kubuntu, this does not happen, and the notifications are more obtrusive. The notification does not dim, so it blocks anything behind it, and blocks mouse clicks.
In ubuntu, the notification popup that occurs in the upper right is unobtrusive, and when you mouse over it, it will dim so that you can see behind it and it will allow you to click on things that are behind it. In kubuntu, this does not happen, and the notifications are more obtrusive. The notification does not dim, so it blocks anything behind it, and blocks mouse clicks.