Please see these earlier posts on SynEdit history:
SynEdit preferred version? - Delphi Third-Party - Delphi-PRAXiS [en] (delphipraxis.net)
Turbo SynEdit & Font Ligatures - VCL - Delphi-PRAXiS [en] (delphipraxis.net)
DirectWrite and Unicode support
One of the major flaws of SynEdit was the poor handling of Unicode. A major update has been committed to the TurboPack fork, that employs DirectWrite for text painting and fixes Unicode support. SynEdit should now be on a par with, if not better than, the best editors around with respect to Unicode handling. For example:
Chinese is properly spaced and surrogate pairs and color emojis are fully supported:
Bidirectional text editing is fully supported as well:
WordWrap has been re-written and is now based on DirectWrite as well. This last update also includes other enhancements as for example an option to alpha blend the selection, another option for selection to cover just selected text instead of full lines, as in VS code and other editors, and horizontal mouse wheel scrolling:
Other recent improvements:
The undo/redo system was buggy and a mess, getting in the way of implementing new features. I has been reimplemented from scratch.
The gutter has been reimplemented from scratch and is now flexible and extensible.
A track changes bar like in Visual Studio has been added and unlike Delphi's it saves and restores line state correctly on undo/redo.
The code base has been refactored cleaned-up, and partially documented, yet, and despite of the new features, it is thousands of lines shorter than the original. But a lot more can be done in this area.
See here for the full list of enhancements in the the TurboPack fork.
Backward compatibility
Turbopack Synedit remains compatible with earlier versions of Synedit, but you do need to reinstall Synedit, load forms that use SynEdit ignoring error messages and save them again for the new properties to take effect. The use of DirectWrite though means that Windows XP is no longer supported. The TurboPack SynEdit fork supports Delphi versions Berlin or later.
Future plans
The next big planned feature is multi-selection and multi-cursor editing.
Support the project
Most of the bugs remaining in the issue tracker are C++Builder related. Also, the C++ packages have not been updated yet. We are actively seeking contributions on the C++Builder side of things (package updates, bug fixes).
Of course you can also support the project by submitting bug reports and pull requests. Or, by implementing new features (e.g. minimap, Sync Edit like in Delphi, Delphi or VS-code like templates etc.)
Note: Many thanks to @MarkShark for his great contributions to the SynEdit project.