"Slider" marker: show 0 values on the marker timeline

[TS-Tino16]

When the slider marker logs annotations and the slider is set to 0 value, then the user cannot see the annotation on the markers timeline.

We need to draw the line of the slider annotation stronger than the markers timeline.

[TS-Stefan]

I thought we discussed this and it was agreed to not show anything when slider values is set to 0.

@TS-Daniel16 do you remember the details?

[TS-Daniel16]

@TS-Stefan there is a difference between the value 0 and no value (null). The value 0 should be displayed to differentiate between these two scenarios. Similar to the range annotation where the annotation rectangle is placed on the timeline, this could be done the same way for the value 0