/// <summary>
/// The Windows group box doesn't erase the background so we do it
/// ourselves here.
/// </summary>
/// <internalonly/>
private void WmEraseBkgnd(ref Message m)
{
NativeMethods.RECT rect = new NativeMethods.RECT();
SafeNativeMethods.GetClientRect(new HandleRef(this, Handle), ref rect);
using (Graphics graphics = Graphics.FromHdcInternal(m.WParam)) {
using (Brush b = new SolidBrush(BackColor)) {
graphics.FillRectangle(b, rect.left, rect.top,
rect.right - rect.left, rect.bottom - rect.top);
}
}
m.Result = (IntPtr)1;
}