Handle "y" parameter correctly when offsetting m_pAlpha, it was just ignored before, i.e. Offset(x, y) and OffsetY(y) always behaved as if y were 1.
Handle "y" parameter correctly when offsetting m_pAlpha, it was just ignored before, i.e. Offset(x, y) and OffsetY(y) always behaved as if y were 1.