This is a Python Tag script that uses a basic Null object to make a nice object manager separator. Change separator’s name in Null object’s User Data and select style and width as you wish.
The script is created to work with Cinema 4D’s default UI font: Segoe UI, Regular 11. Since the font is not a monospace typeface, I had to go through each letter, number and symbol and gave them a custom weight. Weighting is not perfect but it is better than nothing.
N.B. supported characters are very limited.