Alexandre, E.,
would it be possible for you to create a slightly modified version of the KSplash default theme with "rounded" corners? 
I would like to compare a "rounded square" and a "full" square and see which one looks better. I think a rounded 
splashscreen may look a little better at login.
The file to modify are in tdebase/ksplashml/pics/themes/default, probably only splash_top.png and splash_bottom.png

Thanks
   Michele