ui.backend.cocoa: simplify system-alert implementation now that callbacks bug has been fixed
ui.backend.cocoa: simplify system-alert implementation now that callbacks bug has been fixed

mcandre/factor,mcandre/factor,erg/factor,mcandre/factor,erg/factor,mcandre/factor,mcandre/factor,erg/factor,erg/factor,erg/factor,erg/factor,mcandre/factor,erg/factor,mcandre/factor