In FL Studio the ability to add a separator to the track mixer thereby separating the different instruments or track types creates an ease to view them especially if there are many tracks.
I find this feature sorely missing on Ableton Live and though the new update provides groups, there is no easy way to move between groups quickly. By providing a track & mixer separator, with the option to colour code it, it will really help ease the workflow and add ease of viewing the many track types without using groups, which would obviously be clearly demarcated by this separator.