hotkey; flash fixation point

Hi there,
I am interested in adding a hotkey which when pressed, will quickly flash the fixation point to a slightly larger size, and then back to it's starting size -- similar to the "sparkle/S" hotkey in Presentation. I am using a userloop functionality to present a fixation dot, followed by a small movie. It is helpful to the grab the subject's attention during tasks which begin with fixation -- others may find this functionality useful as well . however, I am not sure where to start, given the examples under 'hotkey' in docs. Are there any examples ofhow to manipulate task objects via hotkeys?

attaching userloop & timing file if helpful.

thanks much for your time!
best,
Geena

If you did not notice yet, TaskObjects are not manipulable while being presented, which is why NIMH ML has the scene framework.
https://monkeylogic.nimh.nih.gov/docs_CreatingTask.html#RuntimeVersion2_Background

But you can do something similar with a simple trick. See the attached.