bool IsDoubleWidth(int c)
{
	// This function is taken from Markus Kuhn's wcwidth implementation.
	// For license and implementation details, see:
	// https://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c
	
	return c >= 0x1100
			&& (c <= 0x115F								// Hangul Jamo init. consonants
				|| c == 0x2329
				|| c == 0x232A
				|| (c >= 0x2E80 && c <= 0xA4CF && c != 0x303F)                  // CJK ... Yi
				|| (c >= 0xAC00 && c <= 0xD7A3)					// Hangul Syllables
				|| (c >= 0xF900 && c <= 0xFAFF)					// CJK Compatibility Ideographs
				|| (c >= 0xFE10 && c <= 0xFE19)					// Vertical forms
				|| (c >= 0xFE30 && c <= 0xFE6F)					// CJK Compatibility Forms
				|| (c >= 0xFF00 && c <= 0xFF60)					// Fullwidth Forms
				|| (c >= 0xFFE0 && c <= 0xFFE6)
				|| (c >= 0x20000 && c <= 0x2FFFD)
				|| (c >= 0x30000 && c <= 0x3FFFD)
				);
}