GitHub - antonj/Highlight-Indentation-for-Emacs: Minor modes to highlight indentation guides in emacs.
GitHub - targzeta/linum-highlight-current-line-number: A Emacs function for the `linum-format` variable to highlight the current line number with a custom face.
![overlays - Highlighting selected region in same buffer, displayed in multiple windows - Emacs Stack Exchange overlays - Highlighting selected region in same buffer, displayed in multiple windows - Emacs Stack Exchange](https://www.lawlist.com/images/highlight_nonselected_windows_01.png)