IsFullWidthChar
if (IsFullWidthChar(pos.y, pos.x))
bool IsFullWidthChar(int32 row, int32 column) const;
if (fVisibleTextBuffer->IsFullWidthChar(j - firstVisible, k))
if (fTextBuffer->IsFullWidthChar(j, k))
if (fTextBuffer->IsFullWidthChar(start.y, start.x)) {
if (fTextBuffer->IsFullWidthChar(end.y, end.x)) {