I am using SMPlayer 0.6.8 (SVN r3213) with Qt 4.6.2 (compiled with 4.5.3) and mplayer SVN r31110, precompiled for Debian testing/unstable.
When used with "focus follows mouse", I have to click on the full screen image
before I can use a key command to manage the program. Before I do a click to
focus, the focus is on the program in the background. To experience this,
maximize a text editor and put it behind the kaffeine window.
You can change focus behaviour in KDE with System Settings -> Window behaviour ->
Window Behaviour -> Focus -> Policy -> Focus Follows Mouse. (I tried this with medium focus stealing behaviour. The focus policy is part of X and not specific for KDE.
Also, if the window is not on top and you maximize it, other windows will cover the fullscreen window.
I would like the program to set a new focus on the fullscreen window, and to raise it to the top.