From Gnash Project Wiki
Software tools for Gnash development
Cross development tools
- This is a tarball of cross development tools for OpenEmbedded, which also includes OpenZaurus. Install this in /usr/local/arm/oe.
- This is a tarball of cross development tools for the OLPC, customized for the Geode. Install this in /usr/local/olpc.
- This page describes how to build an optimized tool chain for the OLPC, which is based on an AMD Geode LX.
- This page ha a script that builds GCC4.x as a cross compiler for Mingw32. (win32)
- How to beat your phone into submission
- This is a tarball of cross development tools for the Chumby. The Chumby does come with it's own cross tools, but I found the included packages insufficient. This is a respin of the same binutils/compiler versions as currently used on the chumby, but contains many additional development packages needed for Gnash., like Boost.
Software Tools for SWF/ActionScript
- SWF Tools is a collection of SWF manipulation and creation utilities. The development version includes an AS3 compiler (as3compile).
- Swfmill is an xml2swf and swf2xml processor with support for including HaXe and Mtasc compiled ActionScript, and disassembling SWFs.
- Flasm is a free command line assembler/disassembler of Flash ActionScript
- Flare is a free ActionScript decompiler.
- Ming SWF output library. Includes command-line ActionScript 1 compiler + debugging utils
- MTASC Motion-Twin ActionScript 2 compiler (Server-side web demo)
- Describe SWF A Java based Flash file browser. Can be used to navigate the hierarchical data structures in a Flash file.
- HaXe Web-oriented OO programming language that can be compiled to SWFs, successor to Mtasc. ABC capable!
- hxASM - Generate ABC blocks from assembly code (from HaXe project)
- Adobe's Flex SDK available under MPL license - AS3=>ABC capable. here's a short introduction to get started with it
- AsUnit Unit Test Framework supports testing your ActionScript in Flash Players 6, 7, 8 and 9 but does not currently work in Gnash (sourceforge project site)
- The Adobe Open Source ActionScript 3 libraries that can talk to Flickr, YouTube etc may be interesting
- http://osflash.org/projects/aswing - free UI lib (AS2/AS3) - The AS2 library is MTASC compatible.
- Clash is a fork of Pencil that is aimed to produce a free software Flash authoring software.
- Salasaga - An Integrated Development Environment for producing eLearning (formerly Flame). Licensed under the LGPL. SWF output is improving rapidly (Ming based).
- http://xinf.org - dev ide capable of SWF output
- Open Dialect - a visual editor that uses Flex SDK to produce SWF.
UIRA - A project aimed at building an OpenSource vector animation Authoring Environment (SWF/SVG) in QT4. UIRA is under LGPL. It is the reborn of the now dead F4L project. Shut down. See also wikipedia article 
- Cazabe - GPLv2 IDE
ActionScript Code Editors
- FlashDevelop Integrated Development Environment for ActionScript 2, ActionScript 3 & MXML and HaXe.
- SEPY ActionScript 2 Integrated Development Environment using MTASC
Exporting to SWF
- Open Office Impress - Exports to SWF, supported since gnash 0.8.3
- Pencil is a free software animation GUI for creating bitmap and vector animations that can export to SWF. It will run on GNU/Linux, MacOSX, and Windows.
- Sflender - Blender SWF export. Supported (tested with gnash 0.8.3)
- BuGLe An OpenGL debugger and trace logger
- Valgrind Probably the best tool out there for detecting memory-violations and leaks in run-time.
- Wikipedia Static code analysis tools