There's also FDT, an Eclipse plugin that makes Flex Builder look like a joke in terms of how it deals with Actionscript code. I don't know what it does with MX

There's also FDT, an Eclipse plugin that makes Flex Builder look like a joke in terms of how it deals with Actionscript code. I don't know what it does with MXML though, and haven't tried the debugger in it either (I don't have the so called enterprise version).