this makes kspash be in a rectanle that looks just like the one used now in lockscreen and sddm.
the weird start animation is removed, but the k+progressbar enter from the right (to complete, sddm could have its content sliding to the left before the actual login, not sure is possible)
it also *should* kindof play nice with hig dpi (not tested, a bit trivky since still restricting to pure Qt imports for load times)