Chinese characters are only properly monospaced when font size is a multiple of 3
Issue initially found in Geany, reported upstream to scintilla, further moved up to here.
Using various Chinese monospaced fonts, Chinese characters are only correctly monospaced alongside other characters like letters of the alphabet and typical programming punctuation {}()[]
when the font size is a multiple of 3. A font where this occurs is attached. The maintainer at scintilla noted font widths provided by pango at font sizes 9, 10, 11 and 12:
MeasureWidths [6] '字母' 12 24
MeasureWidths [4] 'abcd' 6 12 18 24
MeasureWidths [6] '字母' 13 26
MeasureWidths [4] 'abcd' 7 14 21 28
MeasureWidths [6] '字母' 15 30
MeasureWidths [4] 'abcd' 7 14 21 28
MeasureWidths [6] '字母' 16 32
MeasureWidths [4] 'abcd' 8 16 24 32
Could either be solved by allowing non-integer dimensions, or by snapping the widths of double width monospaced characters to double the width of the single width characters.
gtk4-4.4.1-1.fc35.x86_64 Also installed, gtk3-3.24.31-2.fc35.x86_64 Fedora 35