Code:
PIXELFORMATDESCRIPTOR pfd = {
		sizeof (PIXELFORMATDESCRIPTOR),             // Size of this structure
		1,                                          // Version number
		PFD_DRAW_TO_WINDOW |                        // Flags
		PFD_SUPPORT_OPENGL,
		PFD_TYPE_RGBA,                              
		24,                                         // 24-bit color
		0, 0, 0, 0, 0, 0,                           // Don't care about these
		0, 0,                                       // Alpha buffer
		0, 0, 0, 0, 0,                              // No accumulation buffer
		32,                                         // 32-bit depth buffer
		0,                                          // No Stencil buffer
		0,                                          // No auxiliary buffers
		PFD_MAIN_PLANE,                             // Layer type
		0,                                          // Reserved (must be 0)
		0, 0, 0                                     // No layer masks
	};
	
if( m_hdc != NULL )
{
	int pixelFormat = ChoosePixelFormat(m_hdc, &pfd);
}
When calling ChoosePixelFormat I get this warning:

"VERIFIER STOP 00000303: pid 0x1994: NULL handle passed as parameter. A valid handle must be used."

The function succeeds, but why this complaint about NULL handle?