Fixed (?) window for sprites...

I'm still not sure about that change: I've made the same
for screens a while ago and it seems to be ok... so...

This fix the Cotton Boomerang title screen.

git-svn-id: https://yabause.svn.sourceforge.net/svnroot/yabause/trunk@3130 d7be59e3-070e-4b9a-85a1-4646befae34d