Not explicitly, but you can get close by changing the color of .waveform (which is layered under .seekBarBefore).

What color are you looking to change it to? Close to the same red color, or something drastically different?

Is it any way of making skinning actions of the part of the seekbar to the right of the thumb? It is with a red marking in the image below.

[img]https://www.gnirpla.se/mm/seekbarafter.png[/img]

The question is if it is possible addressing it similar to the left part (which is is possible addressing with .waveform .seekBarBefore)