PHP-GTK is actually a mini-PHP: it provides the core functionality and API, and a set of extensions for additional features. The Glade support is implemented via an extension. Some other ones in the main distribution are: |d04a21|gdkpixbuf| - provides image loading and rendering functionality |d04a21|scintilla| - a source code editing widget with syntax highlighting, code completion, and much more |d04a21|gtkhtml| - makes HTML rendering and editing possible |d04a21|canvas| - antialiased vector graphics rendering and manipulation |d04a21|extra| - additional widgets for plotting, spreadsheets, etc There are some other extensions created by users, such as GLArea (for OpenGL rendering).