If you have used any of the Dock Applications which allow you to add all your running task into central place where you can launch, Task Dock is one which does it without giving you a feel that it’s not Windows 7 feature. This application center aligns everything on your Windows 7 Taskbar so it looks like you are docking everything to one place.
However if you see your Task bar icons missing it can be accessed using the arrow button which pops at the end of it. This is not a bug, it’s because the area where all these icons are dropped in is limited. Just unlock the taskbar and you would see dotted area which will allow you to expand. Once you set it to max on both the sides the issues will resolve. You would see the dock expanding as you add more application.
Download Task Dock by Solo Dev @ DevianArt
Related : Circular Dock for Windows 7