void ArthurOutputDev::updateFillOpacity(GfxState *state)
{
  QColor brushColour= m_currentBrush.color();
  brushColour.setAlphaF(state->getFillOpacity());
  m_currentBrush.setColor(brushColour);
}

This weakness involves numeric computation errors, such as integer overflows, underflows, or precision losses, which can lead to miscalculations and exploitable behaviors in software.