This mode lets you draw various curve shapes.
Found in: Preferences -> Controls -> Drawing.
Default key: Ctrl-Alt-D.
Additional actions: Increase Sudivision Level, Decrease Sudivision Level.
You can activate this mode by pressing Ctrl-Alt-D (default key).
You can use "Increase Sudivision Level" and "Decrease Sudivision Level" actions to control how detailed the curve is: