List of features of the Pyzo IDE

General

Powerful introspection (see below).
Allows various ways to interactively run code (see below).
Using an intuitive shortcut editor, a shortcut can be created for any item in the menu.
Various handy tools, plus the ability to make your own.
Choose between different Qt themes.
Full Unicode support in both editor and shell (this seems obvious, but was not trivial at the time :)).

The pythonic shells run in a subprocess and can therefore be interrupted or killed.
Several shells can be used simultaneously, and can be of different Python versions (v2.4 - v3.x).
Pypy is supported, Jython and IronPython may be too (untested).
Command history.
Text in the shell can be selected and copied. Text can be pasted to the command line.
The original stdout and stderr are printed to the shell (for C programs that print to file 1 or 2).
It is guaranteed that no stdout or stderr messages are dropped; if the shell cannot keep up with displaying messages, the kernel is slowed down automatically (try while True: print(time.time())).
Debugging next/step/continue.
Post-mortem debugging.
Enables using several GUI toolkits interactively: PySide, PyQt4, Tk, wx, fltk, GTK.
Supports removing previously printed text by using the backspace char.
Supports magic commands similar to IPython.
You can create multiple shell configurations (different Python version, different GUI integration, etc.)
Use 'pip' or 'conda' commands to manage your packages.

Supports auto indentation.
Automatically determines the indentation width when loading a file.
Matlab-style cell system to mark code sections (by starting a line with '##').
Syntax highlighting for Python, Cython, C, and more to come.
todo: Syntax schemes easily editable and extendable
Supports commenting and uncommenting selected lines.
Drag-'n-drop files or directories to open them.
Find/Replace (also supports regular expressions).
The line ending style can be changed.
Optionally use tabs, or insert tabs as spaces.
Indentation guides.
todo: Brace matching.
View whitespace / line endings.
Zooming.
Undo / redo.
Highlighting of current line.
Long line indicator.
Choice of multiple fonts, Pyzo comes with two beautiful fonts by default.
Breakpoints for debugging.

Introspection information is queried from the active shell, and from the source code (by continuously parsing the file in a separate thread). (This is going to be integrated with the syntax parsing)
Auto completion for any object in the active Python session and all __builtins__.
Optional auto completion for Python keywords.
Auto completion for functions, classes, and class attributes defined in the current file in the editor (taking inheritance into account, even if a super class is defined in the shell).
Shows signature of functions (from the shell or from the source) using a call-tip.
Interactive help for all objects in the active Python session by moving up/down the auto completion list, by double-clicking on a name, or by filling in the name directly.
Interactive help show the docstrings of properties (rather than of the returned object).

Run code by typing directly in the interactive shell.
Run selection:
- Run current line if there is no selection.
- Evaluate selection if there is a selection and it is on one line.
- Run all (whole) selected lines if selection spans multiple lines.
Run cell (a cell is the piece of code between two lines starting with '##').
Run current file.
Run main file.
Run current file as a script.
Run main file as a script.

File browser: List all files in your projects by bookmarking the directories of your projects. Easy switching between projects.
Source structure: a tool that lists the structure of the source in a tree widget. It can list classes, functions (and methods), import statements, cells, and todo items.
Interactive help: a tool that displays help information interactively (on selection and scrolling through an autocompletion list.)
Workspace: lists all variables (also in debug mode).
File browser: browse files and search inside files.
Logger: a logger shell that displays Pyzo's log messages and can be used for development or for changing advanced settings.