Add test for generating a colored unicode box which

includes some double-wide characters

test/177_utf8_generate_box.cfg

@@ -0,0 +1,47 @@
+# This config contains UTF-8-encoded elements used correctly, and a simple colored box design.
+
+BOX designA
+
+sample
+    ┏━┳━ 沐宸 若汐 ━┓
+    ┃ ┃             ┋
+    ┃ ┃             ┃
+    ┃ ┃             ┋
+    ┣━╋━━━━━━━━━━━━━┫
+    ┗━┻━━━━━━━━━━━━━┛
+ends
+
+# Monochrome sample (with UTF-8):
+# ┏━┳━ 沐宸 若汐 ━┓
+# ┃ ┃             ┋
+# ┃ ┃             ┃
+# ┃ ┃             ┋
+# ┣━╋━━━━━━━━━━━━━┫
+# ┗━┻━━━━━━━━━━━━━┛
+
+shapes {
+     n (" 沐宸 若汐 ",
+        "           ")
+     nw ("┏━┳", "┃ ┃")
+     nnw ("━", " ")
+     nne ("━", " ")
+     ne ("┓", "┋")
+     e ("┃", "┋")
+     w ("┃ ┃")
+     se ("┫", "┛")
+     s ("━", "━")
+     sw ("┣━╋", "┗━┻")
+}
+
+elastic (
+    nnw, nne, e, w, s
+)
+
+padding {
+    horiz 1
+}
+
+replace "ä" with "ö"
+reverse "ö" to "ä"
+
+END designA

test/177_utf8_generate_box.txt

@@ -0,0 +1,17 @@
+:ENV
+export TERM="xterm-color"
+:ARGS
+-f 177_utf8_generate_box.cfg -s 21x8 -ac
+:INPUT
+fäo
+:OUTPUT-FILTER
+:EXPECTED
+┏━┳━━━ 沐宸 若汐 ━━━┓
+┃ ┃                 ┋
+┃ ┃                 ┃
+┃ ┃       föo       ┋
+┃ ┃                 ┃
+┃ ┃                 ┋
+┣━╋━━━━━━━━━━━━━━━━━┫
+┗━┻━━━━━━━━━━━━━━━━━┛
+:EOF