POINT p1, p2, delta;
BOOL b_Drawing;

void CtestrectDlg::OnMouseMove(UINT nFlags, CPoint point)
{
	
	CDC *pdc = GetDC();
	RECT rc;
	CBrush cbr;
	
	cbr.CreateSolidBrush(RGB(128,128,128));
	GetClientRect(&rc);
	
	pdc->FillRect(&rc, &cbr);
	
	if(b_Drawing){
		cbr.CreateSolidBrush(RGB(128,128,255));
		pdc->SelectObject(&cbr);

		delta.x = abs(delta.x - point.x);
		delta.y = abs(delta.y - point.y);

		p2.x = p2.x - delta.x;
		p2.y = p2.y + delta.y;

		pdc->Rectangle(p1.x, p1.y, p2.x, p2.y);
		
	}

	delta.x = point.x;
	delta.y = point.y;
	
}

void CtestrectDlg::OnLButtonDown(UINT nFlags, CPoint point)
{
	p1.x = point.x;
	p1.y = point.y;

	p2.x = p1.x;
	p2.y = p1.y;

	b_Drawing = TRUE;
}

void CtestrectDlg::OnLButtonUp(UINT nFlags, CPoint point)
{
	b_Drawing = FALSE;
}