Try an xposed module like menubegone or wanam with an option to disable the app 3 dot menu.
didn't work...got that same stupid floating window...even uninstalled S5 Toolbox addon and even unchecked toolbox in settings...found out this is not toolbox...it's a floating menu button...which can't be disabled...and in some apps...2 copies of it appear...I tried experimenting with freezing certain apps in TB and even attempting to see which process the menu ran under by process of elimination in killing tasks quickly. It's more complicated then freezing / uninstalling a certain process..
also most lockscreen options including shortcuts are borked. don't try em.
this is awesome though that Super Power Saver Mode was ported...this is excellent but the battery life could be better,,,I disabled most allshare and other things LBE Security Master said was running.and lulz...some useless fingerprint modules haha...but here's something I thought of...do we still need to calibrate a battery after a ROM flash?...i haven't done it in a while since ICS but i'm wondering if it still helps by this point. Also would ART compared to dalvik use more battery? I heard that battery life will improve after a few days so i'm going on that