well, I am sure that level of smoothness could be matched with some effort... The name of it (CurveTo) implies that it is calculating curves between mouse positions. My example below just draws from position to position, so it is not as smooth.
This paint program was started by my son - he wanted to make a game where you draw your own weapon. I cut out the weapon parts (he had templates to trace and standard parts you could drop in, and then let you try it out).
I made it draw in a random color, and added a small random amount to the line thickness to help smooth out the line a little.
Use the scroll wheel to increase or decrease the pen thickness. The right mouse button erases, the left draws.
(This requires ROJOhounds Canvas plugin).