There are still problems for languages like Javanese but it will improve most
cases.
Unicode proposal to improve line breaking:
https://www.unicode.org/L2/L2022/22080r2-line-break-ortho-bnd.pdf

explicit swap chain and ID2D1DeviceContext.
Stop supporting DirectWrite on Windows Vista.

 and HiDPI screens
The GDK_RIGHT_PTR cursor is provided only by GTK - there's no native
Windows cursor of this shape so GTK renders the cursor by itself from
the cursor theme bitmap. The code doing this is apparently buggy and
does not take into account HiDPI screens so on a screen with 300% scaling,
the cursor is 3x smaller.

Workaround this by using GDK_HAND2 which maps to a native Windows cursor
that doesn't suffer from this problem.

See https://sourceforge.net/p/scintilla/bugs/2460/

that must be drawn with their base letters.
This is only a subset of implementing grapheme cluster boundaries but it
improves behaviour with some Asian scripts like Thai and Javanese.
Javanese is mostly written with (ASCII) Roman characters so issues will be rare
but Thai uses Thai script.
Also slightly improves placement of combining accents in European texts.
https://github.com/notepad-plus-plus/notepad-plus-plus/issues/14822
https://github.com/notepad-plus-plus/notepad-plus-plus/issues/16115

SCI_SETSELECTIONSERIALIZED.

consistent as 'undo selection' instead of 'selection undo' as more closely
associated with undo than selection.