East Asian wide characters in the Supplementary Ideographic Plane (thanks to
http://www.i18nguy.com/unicode/supplementary-test.html):

𠜎𠜱𠝹𠱓𠱸

Mixed East Asian wide characters from the BMP and SIP:

中文：𠜎𠜱，你好，𠝹国。
𠱸，中文：你好，𠝹国。

Narrow characters and mixed east Asian wide characters from the BMP and SIP, in
an 80-column line:
xxxxxxxxxx中文:𠜎𠜱，你好，xx𠝹国。xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx你好xxxxxxxxxx
xxxxxxxxxx𠱸,中文：你xx好，𠝹国。xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx好

Overwriting an East Asian wide character from the SIP with a narrow character:

中文：𠜎 ESC [ 2 D x:
中文：𠜎x

xxx中文：𠜎 ESC [ 2 D x:
xxx中文：𠜎x

Overwriting an East Asian wide character from the SIP with a narrow character,
in the middle of an 80-column line with mixed narrow and wide chars:

xxx[...]xxx中文：𠜎xxx[...]xxx你好xESC [ 27 G y:
xxxxxxxxxxxxxxxxxxxx中文：𠜎xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx你好xy

xxx[...]xxx中文：𠜎。xxx[...]xxx你好ESC [ 27 G y:
xxxxxxxxxxxxxxxxxxxx中文：𠜎。xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx你好y

Overwriting an East Asian wide character from the SIP with an East Asian wide
character from the BMP:

中文：𠜎 ESC [ 2 D 国:
中文：𠜎国

xxx中文：𠜎 ESC [ 2 D 国:
xxx中文：𠜎国

Overwriting an East Asian wide character from the SIP with an East Asian wide
character from the BMP in the middle of an 80-column line with mixed narrow and
wide chars:

xxx[...]xxx中文：𠜎xxx[...]xxx你好xESC [ 27 G 国:
xxxxxxxxxxxxxxxxxxxx中文：𠜎xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx你好x国

xxx[...]xxx中文：𠜎。xxx[...]xxx你好ESC [ 27 G 国:
xxxxxxxxxxxxxxxxxxxx中文：𠜎。xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx你好国

Overwriting an East Asian wide character from the BMP with an East Asian wide
character from the SIP:

中文：国 ESC [ 2 D 𠜎:
中文：国𠜎

xxx中文：国 ESC [ 2 D 𠜎:
xxx中文：国𠜎

Overwriting an East Asian wide character from the BMP with an East Asian wide
character from the SIP in the middle of an 80-column line with mixed narrow and
wide chars:

xxx[...]xxx中文：国xxx[...]xxx你好xESC [ 27 G 𠜎:
xxxxxxxxxxxxxxxxxxxx中文：国xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx你好x𠜎

xxx[...]xxx中文：国。xxx[...]xxx你好ESC [ 27 G 𠜎:
xxxxxxxxxxxxxxxxxxxx中文：国。xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx你好𠜎

Inserting a narrow character into the middle of an East Asian wide character
from the SIP in the middle of an 80-column line with mixed narrow and wide
chars:

xxx[...]xxx中文：𠜎xxx[...]xxx你好xESC [ 28 G y:
xxxxxxxxxxxxxxxxxxxx中文：𠜎xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx你好xy

xxx[...]xxx中文：𠜎。xxx[...]xxx你好ESC [ 28 G y:
xxxxxxxxxxxxxxxxxxxx中文：𠜎。xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx你好y

Inserting an East Asian wide character from the SIP into the middle of an East
Asian wide character from the BMP in the middle of an 80-column line with mixed
narrow and wide chars:

xxx[...]xxx中文：国xxx[...]xxx你好xESC [ 28 G 𠜎:
xxxxxxxxxxxxxxxxxxxx中文：国xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx你好x𠜎

xxx[...]xxx中文：国。xxx[...]xxx你好ESC [ 28 G 𠜎:
xxxxxxxxxxxxxxxxxxxx中文：国。xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx你好𠜎

Inserting an East Asian wide character from the BMP into the middle of an East
Asian wide character from the SIP in the middle of an 80-column line with mixed
narrow and wide chars:

xxx[...]xxx中文：𠜎xxx[...]xxx你好xESC [ 28 G 国:
xxxxxxxxxxxxxxxxxxxx中文：𠜎xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx你好x国

xxx[...]xxx中文：𠜎。xxx[...]xxx你好ESC [ 28 G 国:
xxxxxxxxxxxxxxxxxxxx中文：𠜎。xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx你好国