See this discussion for more: #2939

What's broken today (v2):

• Combining Marks that don't normalize are not supported
  • /u0301 at column 0 renders ́ even though /u0301 is a zero-width codepoint.
  • a/u0301 works because ConsoleDriver normalizes it á
  • a/u301/u0301 doesn't work. ConsoleDriver normalizes it to á and ignores the 2nd /u0301.
  • TextField/TextView` strip out CMs on paste.
• non-BMP characters
  • WindowsDriver
    • Not supported by Windows Terminal when using the WriteConsoleOutput (what WindowsDriver currently does). WindowsDriver currently outputs non-BMP characters as Rune.ReplacementChar
  • CursesDriver
    • Single-width non-BMP chars output as a space
    • Wide non-BMP characters are output as *
  • NetDriver
    • Single-width non-BMP chars correctly
    • Wide non-BMP characters chars output correctly

Note, TextView/TextField and other input views do not handle any of this stuff correctly (mostly).

Related:

• Refactor ConsoleDrivers to support ANSI sequences natively (e.g. Virtual Terminal Sequences on Windows) #2610