Graphics.FillRectangle() didn't work

Graphics gp = Graphics.FromHwnd(p2pPic.Handle);

SolidBrush sb = new SolidBrush(Color.DodgerBlue);

lock (gpPalette)
{
     gpP.FillRectangle(sb, aRectangle);
}

p2pPic is a PictureBox object in c#; these are the main开发者_运维百科 code ,and code does run, but did not take any effect who can tell me why?

---

Depends where you have placed this code. PictureBox would eventually do its own painting.