However I found that I had to enable double buffering for all controls in my application, just enabling it for the DataGridView was not sufficient.

What I did was this:

Change your extension method to work on Controls:
public static class ExtensionMethods
{

public static void DoubleBuffered(this Control control, bool setting)
{
Type dgvType = control.GetType();
PropertyInfo pi = dgvType.GetProperty(“DoubleBuffered”, BindingFlags.Instance | BindingFlags.NonPublic);
pi.SetValue(control, setting, null);
}
}

And call it for all controls in my app in the constructor of the main program: DoubleBuffer(this):

protected void DoubleBuffer(Control control)
{
control.DoubleBuffered(true);
foreach (Control c in control.Controls) { DoubleBuffer(c); }
}

I have been developing a C# program to communicate with an amateur radio modem (PK-232) via a serial port and struggled with the rich text box scrolling issue until I found this very elegant solution.
I can not believe that this is not part of the rich text box class…

Thank you VERY much….
DenS

Thank you very much
You really saved me

good luck