Recording Response Time and History when using keys for a slider

OS (e.g. Win10):
PsychoPy version (e.g. 1.84.x): 2022.2.05

I want to use the keyboard on a slider (like [here]). I implemented it as follows, but it only recorded the slider position, not the response time (i.e. first movement of slider) or the history of the slider. I marked “store rating time” and “store rating history” in the slider event. So that is not the problem.

keys = event.getKeys()

if len(keys):
    if 'b' in keys:
        slider_vignette.markerPos -= 1
    elif 'g' in keys:
        slider_vignette.markerPos += 1 
slider_vignette.rating = slider_vignette.markerPos

For the rating time I tried:

keys = event.getKeys(timeStamped=True) 

And then to slice like keys[0] for the response and keys[1] for the response time. I get: IndexError: list index out of range.
For the history my problem is that I want to store the position of the slider, not the keys I pressed. Therefore I am even more lost on this part.

Could you please help me out how to best solve that?