The ornamental design for a universalchildsafetytensioner for a roller blind, as shown and described.
FIG. 1 is a perspective view from the bottom of the universal child safety tensioner for a roller blind.
FIG. 2 is a perspective view from the top of the universal child safety tensioner for a roller blind.
FIG. 3 is a front view of the universal child safety tensioner for a roller blind.
FIG. 4 is a back view of the universal child safety tensioner for a roller blind.
FIG. 5 is a right side view of the universal child safety tensioner for a roller blind.
FIG. 6 is a left side view of the universal child safety tensioner for a roller blind.
FIG. 7 is a bottom view of the universal child safety tensioner for a roller blind, the broken lines depicting environment that forms no part of the claimed design; and,
FIG. 8 is a top view of the universal child safety tensioner for a roller blind.