When I start the launcher, it appears behind other windows, just like a general plasmoid.
Can I put it on the top?
It seems that...
Tested with the Rosa-laucher 2.0.0, Raring, KDE 4.10.5
It seems that the problem is the window focus.
KDE System Settings > Window Behavior > Focus tab.
If the focus is 'under mouse' then the Rosa-launcher appears on the top - at here