Options / Color / Define colors by file type... / Add.. / &Define... / Search for: "Temp" / Save / Save "Temp color" / (Choose Temp from the list) / Ok / (Choose a color) / Ok / Ok
I switched to Linux, bye and thanks for all the fish!
Yes it is, when you do as SanskritFritz described, search for *.mp3 after clicking 'define' and then only files with the matching extension will be coloured.
You can also enter multiple extensions to color similar items with the same color, e.g. with searching for *.mp3 *.wav *.wma