Black flicker on form when changing opacity to make fade-in/fade-out

This problem occurs in a Windows form, when you are trying to do fade-out/fade-in say on mouseLeave mouseEnter , sometimes the form display a brief black flicker, even though you set doublebuffer to true, the black flicker continues.

Language Platform: C#,VB, C++ ..etc

Main:

The solution to try is to never let the opacity level reach 1 (100%), make it stop at (99%) or (0.99d, same thing). If still there are some flickers, make sure you set doublebuffer = true.