SetHintMaskAt
void SetHintMaskAt(uint32 x, uint32 y,
fField->SetHintMaskAt(fKeyboardX, fKeyboardY, hintMask);
fField->SetHintMaskAt(x, y, hintMask);
fField->SetHintMaskAt(x, y, hintMask & ~valueMask);
fField->SetHintMaskAt(x, y, validMask);
fField->SetHintMaskAt(x, y, hintMask);