WMC-style timeshift buffer indicator

I would like (for a skin) infotags that show:
– the start of the timeshift buffer
– the current position being played (this is just Player.Progress)
– the end of the timeshift buffer

all as percentages of the program’s time from start to end. That way a skin could show a slider with a graphical indication of timeshift buffer coverage on the scale of the whole program, in the (IMHO) simple and intuitive way that WMC does.

For recordings, “start” and “end” are the start and end of the whole recording.
For programs being recorded, “start” and “end” are the start and end of the part of the program that has been recorded so far, shown on the scale of the whole program (the slider represents the whole program)