DrPython is a highly customizable, extensible editor/environment for developing programs written in the Python programming Language. It is implemented in wxPython.
(wxPython is a set of python bindings (and extra widgets) for wxWidgets).
It uses Scintilla for the Text Controls.

Feature List:

Cross Platform
Works anywhere wxPython works, adopts the native look and feel of the host os.

Built with Scintilla
Syntax Highlighting and Styling Built In
(Support for Python, C/C++, HTML, Plain Text.)
Folding
Drag and Drop for Files and Text
Brace Matching
Rectangular Selection
All wxStyledTextControl Commands can be set via shortcuts, and can be added to the pop up menu.

Built In Prompts
Run the python interpreter, programs in their own process.
Open as many interpreter/program panels as you want.

Highly Customizable:
Edit Syntax Highlighting, Tab Width, Printing Options, Default Find/Replace Flags,
Folding, Default Python Arguments, Automatic File Backups, Feedback Messages,
Toolbar Icons, Python (and wxWidgets) Documentation and more.

Optional Unicode/Encoding Support (with unicode version of wxPython).

Easy Access to DrPython Commands:
Customize the Right Click Pop Up Menu, Keyboard Shortcuts, and an optional ToolBar.

Extensible in Python
Plugins have complete access to DrPython internals.
They can be loaded automatically on startup, or loaded in groups via the menu.
Built in methods to facilitate adding plugin functions to the pop up menu,
keyboard shortcuts, and the toolbar.

Plugins can be installed locally via zip or main plugin file, or downloaded and
installed from sourceforge mirrors.

Scriptable in Python
Quickly write custom python scripts with access to DrPython internals, and access them from the menu,
shortcuts, the pop up menu, or the toolbar.

Quick Access to Files
Bookmarks (which are built into the File Dialog) provide
quick access to files and directories.
The "Open Imported Modules" dialog enables you to
get at modules imported in the document.

Navigate and Manipulate Python Source With Ease
Source Browser:
Shows document classes, function definitions and import statements.

Source Browser Go To:
A mix of find and the source browser in a nifty dialog.
Move quickly to a specific class, function definition or import statement.

Go To Block/Def/Class Start/End:
Move quickly to the start or end of the current function, class, or block of code.

Uses a Custom FindReplace Dialog that supports (beyond the default wxWidgets dialogs):
In Selection
From Cursor
Prompt on Replace
Regular Expressions
Includes a Menu Driven Regular Expression Builder
You can Specify Default Options for Find/Replace/Switcheroo in Preferences.
A Pop Up Menu That Let's you:
Insert Tabs/Newlines/Carriage Returns
Find History
Find and Replace in Rectangular Selection.

Find And Complete
Select from all possible completions of the current word in the current document.
Find And Complete is context sensitive, it forms the list of possible completions
based on the context of the current word.

Further Features are provided by Plugins
Including:
Powerful Find and Replace in Files (SearchInFiles)
Autocompletion (Codecompletion)
Calltips (Codecompletion)
Abbreviations (like in Scite)