I'm running win 8.1 here´s my nexus setup so far : http://i.imgur.com/FCfKala.png

I have 2 problems :

In the pic I have spotify and firefox open, how can I change it so it doesn't create another 2 icons on the right? Just use the app icon as the minimizer instead. Like on mac osx.

That space in the middle.. I have no idea what it is or how to erase it.. if I switch themes it looks like a tab separator, but I can't erase it.

thx.

Answer to first question:
Open WorkShelf Preferences, select the Dock in question and press Properties.
A new window will open, select tab Content (normally already selected).
Under Running applications, uncheck the box next to 'Show running applications in this dock'.

Answer to second question:
Will be solved once you have performed the instructions given above.
(I guess the empty space/icon is used to separate the running application icons from the normal dock icons.)

That's not what I meant, sorry.

For example :

EDIT : I MADE A GIF WITH ANOTHER DOCK THAT ALOWS THIS : http://i.imgur.com/FwOQjlN.gif JUST LIKE THIS BUT ON THE NEXUS DOCK, REASON WHY IS BECAUSE THE NEXUS DOCK AS ALOT MORE POWER AND HAS SOME FEATURES SOME PROGRAMS DONT.

On the image the application icons are on the left, let's say I want to open spotify, I click on the icon and it opens, now I still want to minimize the running spotify to the dock.. but I don't want to add another spotify logo.

Can I just minimize the running spotify to the original spotify icon in the dock? so if I click it again instead of opening a new spotify it maximizes the running spotify.

Also How do I change the blue icon? I believe it's the running taskbar icon replacement, it looks very small and 2007ish in terms of design and it's driving me insane.

Open WorkShelf Preferences, select the Dock in question and press Properties.
A new window will open, select tab Content (normally already selected).
Under Running applications, uncheck the box next to 'Show running applications in this dock'.
(Optional: check the box next to 'Show indicator on shortcuts to applications that are currently running').
Select tab Behavior and under Launching check the box next to 'Do not launch multiple sessions'.

Now you can launch for instance spotify from the dock. If you minimise spotify it will minimise to the task bar.
You can however maximise spotify again by either clicking on its icon in the task bar or its icon in the dock.
These settings will prevent you to start a second instance of spotify from the dock.

With the blue icon I assume you mean the Nexus icon.
Right click on it and select Dock entry properties, then press Change Icon (at the bottom) to change its icon.