KoolDock is a nice app docking application.

As I don't want to have any icons on the screen background because they 
are hidden by other running program, I added the apps I use the most in it.

I placed it at the top of my second screen and set the auto-hide feature on.

So even while running a program in full screen I just have to "touch" 
the top of the screen with the mouse to make it appear and start an 
other program.

Well, it is old (since KDE 1.4) but it is easy to use, slim, very 
reliable and has a nice look.

I used it for years with TDE and thought it was a nice goody to give as 
a contribution.

For more information:

https://store.kde.org/p/1081070/

Enjoy it!

Cheers,

Pascal