With the new taskbar preview feature added in the Windows 7, navigate around all the open tab now require one more click from the thumbnail after you click on the icon on the taskbar. If you have been using Windows for a long time you might not get use to this. So here is a way you can fix by only clicking the icon once and that will open the last active window of the same type program without clicking on the preview thumbnail again.
Here is how you can save the extra Click
To start you need to go to registry and navigate the following path
now right click on the left empty space and add a new 32-bit DWORD value
Rename the new value to LastActiveClick
give the new value 1
When you finish you it should be looking some thing like the first image
Because you have changed the registry you need to log out and log back in again in order for the new change to take effect.
There you have it, now you can just click once on the taskbar and it will jump you to the last active window.