Not really a library but ...
BasicIDE Suite 2 - Now with on-device visual designer and syntax highlighting editor!
BasicIDE Suite 2 is now deprecated in favour of the newer BasicIDE Suite 3 BasicIDE Suite 3 - Now further improved | B4X Programming Forum BasicIDE version 5.2 now includes an improved editor with syntax highlighting, runtime error indication and autocompletion. You need the new CodeEditorView...