Other useful features included are:
- Search and replace using Regular Expressions.
- "Find in Files". Handy for searching for a string or pattern across multiple files and directories.
- Block-select mode / rectangular block selection. Select and manipulate columns of characters, without selecting the entire row(s).
- Bracket matching, auto indentation, and compiler integration.
My 2nd choice would be SciTE. While it has native support for both Win32 and X11 for Linux, the default options aren't the most favorable, and most preferences have to be set through a config file only, since the GUI options are a bit limited. (Read more on Wikipedia: SciTE.)
Both Notepad++ and SciTE seem far better than two other editors I had been using: TextPad (Wikipedia) and EditPlus (Wikipedia). Neither are free nor open source. Neither support code folding. EditPlus supports basic syntax highlighting by default, as does TextPad, but only after adding a syntax definition file.