SUMMARY All non-BMP characters, from U+10000, are treated as double-width STEPS TO REPRODUCE 1. Display a few characters, e.g. U+10400 <𐐀> 2. 3. OBSERVED RESULT Characters are wide EXPECTED RESULT narrow / single-width SOFTWARE/OS VERSIONS various versions, Linux and Windows/cygwin
Probably a font issue. On my system, 𐐀 renders and is treated as single-width. On Linux using fontconfig you can see the fonts that include a character with: fc-list ':charset=10400' Which in my system returns: /usr/share/fonts/noto/NotoSansDeseret-Regular.ttf: Noto Sans Deseret:style=Regular What is the result on your system? Can you try with the Noto fonts?
/usr/share/fonts/microsoft/seguisym.ttf: Segoe UI Symbol:style=Standard,Normal,obyčejné,Κανονικά,Regular,Normaali,Normál,Normale,Standaard,Normalny,Обычный,Normálne,Navadno,Arrunta /usr/share/fonts/unifont/unifont_upper.ttf: Unifont Upper:style=Medium This is on Cygwin/X in Windows. How would I configure X to use the font? Which font to download? Noto provides lots of subfonts for script ranges, how about a single complete installation instead? In any case, I do not think character width should depend on the font setting. A general assumption is that character width is consistent with the system locale.
It may not be a font issue after all. Looking at both fonts, Unifont appears to be fixed-width all around and have a single width 𐐀, and judging from https://catalog.monotype.com/font/microsoft-corporation/segoe-ui-symbol/regular 𐐀 doesn't seem to be much wider than regular latin letters, and is certainly less wide than an M. Can you provide an screenshot?
Created attachment 138834 [details] screenshots with two terminals
Fixed by https://invent.kde.org/utilities/konsole/-/commit/5128781a824c26dc2746650fea0ae9f95861b9d8 Cygwin's konsole version is v17.12.3, which is ancient. All KDE packages in Cygwin are orphaned, see https://cygwin.com/cygwin-pkg-maint and https://cygwin.com/pipermail/cygwin-apps/2020-March/039877.html