Geany is a GTK2 (GUI) text editor which is light and featureful. Here is a sampling of features from their about page:
- Syntax highlighting
- Code folding
- Symbol name auto-completion
- Construct completion/snippets
- Auto-closing of XML and HTML tags
This is a editor that does such magical things as use control up/down to skip paragraphs. I love it for in-page bookmarking, code folding, search-replace, escaped-replaces and regular expressions for selections, documents and groups of documents.