Click with your right mouse button on a window decoration or use System Settings to access the new and easier configuration of KWin. Here you can enable effects to more efficiently manage your windows. You can for example use the Present Windows as the effect for window switching. Instead of showing you icons or very small previews of your applications, it arranges them in a grid so you can quickly choose the right one. Just use the Alt-Tab keysequence and keep the Alt key pressed. You can now use tab to switch through the windows or just activate the right one using the mouse. Hitting Alt-Tab keys quickly will show you the next window in the queue, just like it used to.
