I've just switched from Windows to Mac and need to find a few tools to replace those that were Windows-only. I'm most familiar with FlashDevelop, which I've used for years, but it is Windows only. SEPY seems to have been abandoned, FlashIDE's editor seems weak, and I don't want to purchase FDT or FlexBuilder right now.
I would like an editor that is as good as FlashDevelop at auto-completion and syntax highlight for AS3 and MXML, is highly customizable, and can thus be configured to call external scripts and applications, such as ant, javac, mxmlc, and python with a custom button or hotkey. Also, it would be great if it is lightweight and isn't too pushy about using it's own project folder/management like Eclipse/FlexBuilder/FDT. I often only need to build a single AS3 file or MXML file and don't like the project setup time or having my own folders littered with project metadata files.
Can you recommend a couple of really good AS3 and MXML editors for Mac?
Textmate is your guy. Super lightweight, infinitely customizable with loads of lovely plug-ins and "bundles" (syntax, auto-complete, snippets, macros, commands). There's an AS3 bundle as well that adds ant, mxmlc, etc. It's also really fun to make custom color-highlighting for. It's not for everyone–it's definitely very lightweight (don't expect an IDE), but if you work with it for awhile, you'll see why it's one of mac-user's favorites.
Edit:
Coda is a sexy little app by Panic (makers of Transmit FTP, the de-facto ftp program for Mac) that wraps css editors, text editors, a terminal window, FTP, and more into one tab-paneled application. I personally found it to be too stripped down in each department, but it does make a great application overall if it suits your needs. I know a few programmers and project managers who use it and love it.
Also, Xcode (the free Mac development IDE) can be very nicely configured to work with AS3. I've been developing with it in Objective-C recently and the code-completion and hinting is brilliant. If you can get something like the following rocking with AS3, it could be pretty badass.
http://blog.joshbuhler.com/xcodeflex/
and
http://opencode.forabettertoday.org/?p=3
Other than that, your options are pretty limited until FlashDevelop comes to Mac. I know that using Flash's editor sure as heck isn't an option! They might as well not include it in the next Flash! ;)