this one was bugging me for quite a while. i searched for it in my kde system settings / control panel and couldnt find it. i finally decided to move myself and research a bit and voila! it is solved!first of all, what am i talking about? its when you hover your mouse cursor over the application's name in the task bar. when you do that you get a live preview of the application. and when i say live, i do mean live, if you are watching a video or an animation, the preview will update in real time.
it will also take a few seconds to close once you move your mouse cursor away.