Repaint failure

[VladimirF]

Like Martin suggested (above), a sample might help. Or at least some complete real code fragment.

	case WM_PAINT:
		if (GetActiveWindow() != hWnd) InvalidateRect(hWnd, &re, 0);
		dc = BeginPaint(hWsbox, &ps);
		SelectObject(dc, hBm);
		BitBlt(dc, ps.rcPaint.left,
			ps.rcPaint.top, 
			ps.rcPaint.right - ps.rcPaint.left,
			ps.rcPaint.bottom - ps.rcPaint.top,
			sdc, ps.rcPaint.left,
			ps.rcPaint.top + (scroll ? si.nPos * (SEL_RY + fhgt) : 0),
			SRCCOPY);
		EndPaint(hWsbox, &ps);
		break;

What is hWsbox here? Is it the same as hWnd?
What is hBm? And why do you select it into dc before BitBlt'ing into it?