Why does my transparent Panel whose parent has a gradient background flicker a lot when resized?

Make sure to set these flags for your panel, in it’s constructor (for example).
You will have to derive a class from Panel otherwise if you were initially using the Panel directly.

 
class NonFlickerPanel : Panel
{
	public NonFlickerPanel()
	{
		SetStyle(ControlStyles.DoubleBuffer | ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint,true);
		UpdateStyles();
	}
}