FlashDevelop – essential developing environment
Overview

FlashDevelop is awesome tool which is used as developing environment. I've been using it for a great deal of time now. It has nice organised and intuitive interface, it's easy to set up, and the best of all, it gives you ton of features that you don't have implemented in Flash. I'm talking here about Flash CS3 since I possess it. Some of my best features I'll be covering in this article.
With nice looking environment and tons of features you would expect some price. But fortunately for us developers, FlashDevelop is free. If you want, you can support the project and donate through PayPal (they deserve it).
Features
Like I said, there are a lot of features which are really useful when writing your code. I'll cover only some of them. Complete list of features you can find in FD (FlashDevelop) tour section: list of features
1. Code completion
This one is really time saver! I've been working with C# for a while, and I loved it's IntelliSense. That is really one thing that Flash misses and I, as developer, miss even more.
In Flash you have a little bit of code completion functionality. As I noticed, code completion only shows when you do import classes or when you name your variable with sufix txt, mc and btn (i.e. myTextField_txt). If you miss one letter when writing your code code completion in Flash will close, which is not the case in FD (it will stay open and offer possibilities).
Great thing is that when you import classes, you can write only final class name, and not whole package to get to final class which you want to import like in Flash.
Beside having offered object name in code completion, it also includes graphical presentation of function, getter/setter, private and public variable, etc. (simple icon which is very useful when choosing some variables or functions with identical name).
2. Code navigation
Great thing is that you can follow your variables, functions and everything else in Outline window. I don't use it very often, but it is handy when I need to find something fast. You can click on element and program brings you to it's declaration.
You can bookmark line in your code, and then you can view all bookmarks in Bookmarks window.
Files window is sort of files explorer, and I don't use it, but it can be useful.
On the other hand, Project window is always when I'm working on my projects. Project window contains all files in your project structure. In fact it is folder of your project. From here you can inspect all files in your project, open them, rename, delete, etc.
3. Documentation generation

Lots of people aren't fans of documenting your code. I find it as general mistake since I know how hard is to get back on the project that you haven't work on for a long time.
For those smart enough to comment code, FD supports one neat feature. It is not default integrated but it is pretty simple to install. You can comment your code in Javadoc comments and click GENERATE ASDOC button in FlashDevelop. You have your ASDoc documentation for your classes. Really good way to make the best documentation for your code.
Final thought
These are just 3 general features that I use the most.
One thing I miss is debugger. I still use Flash debugger since it is really good. But even without debugger, this piece of work is best developing environment I've worked on. And it is free!
For more information on FlashDevelop visit FlashDevelop wiki pages or FlashDevelop forum.