do not show the "hint" bubble when no hint is available (#2908) (#2909)
do not show the "hint" bubble when no hint is available (#2908) (#2909)


switchinnovations/pxt,Microsoft/pxt,switchinnovations/pxt,playi/pxt,switch-education/pxt,Microsoft/pxt,Microsoft/pxt,switchinnovations/pxt,playi/pxt,switch-education/pxt,switch-education/pxt,Microsoft/pxt,switchinnovations/pxt,switch-education/pxt,playi/pxt,switch-education/pxt,playi/pxt,Microsoft/pxt