안녕하세요. 윈도우 프로그램은 초보라서 문의드립니다.

아래와 같이 총 30개의 paintbox를 루프를 돌면서 사각형을 그리고 있습니다.
아무래도 paintbox가 많다보니 그리는게 보입니다.

canvas에 그릴때, 그리는 동안은 갱신이 안되고 최종루프가 다 돌고 한번에 보이게 하는 방법도 있는지 궁금합니다.
초보다 보니 기초적인 질문일수도있습니다.
조언부탁드립니다.

for( int i = 0; i < row; i++ ) {
        for( int j = 0; j < col; j++ ) {
            pbGroup1->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup2->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup3->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup4->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup5->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup6->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup7->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup8->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup9->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup10->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup11->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup12->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup13->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup14->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup15->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup16->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup17->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup18->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup19->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup20->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup21->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup22->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup23->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup24->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup25->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup26->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup27->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup28->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup29->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
            pbGroup30->Canvas->Rectangle(0 + (j * 10), 0 + (i * 10), 10 + (j * 10), 10 + (i* 10));
        }
    }