C# Creepy very creepy Flicker, simple square shapes? How to eliminate without buffering?

Question

C++ / C#

How does it even happen.
Just do not advise me doubleBuffered to draw 4 lines, is it such a difficult operation that I can see how they are drawn? And this is C# sharpened for graphics.

Question 2. Also, how does double_buffered work and what is this property?
I've always implemented double buffering myself, is this property some kind of simple implementation?

Answer 1

I don't know about the first one.
about the second drawing goes to the buffer, and then flips to the memory of the control. everything is very fast and without flirting