Lol really... i've found it!
I Apologize with Demeos but i actually thought this was a bug!
Really, i'm really sorry Demeos

The button is "Accessibility Settings" and is actually the last one at the bottom of "System Configurations"
Inside this settings you can enable (and to me it was enabled, don't know why!) and disable this switch "Enable visual alerts"

if Visual alerts are enabled you get this weird behaviour..

Thank you all for the support, and pls forgive me Demeos for not trusting you >_<

hope this helps someone else with the same problem!