+1  A: 

There isn't a configuration setting in FlexBuilder (that I know of) so the only way I can think of to do it would be to replace whatever Java classes in Flex Builder plugin that deal with the variables pane and the debug output with custom ones that you've written to do what you are looking for. Since it's closed source it would have to be a clean room implementation, which would be tough. I've seen some examples of people replacing the java classes in Flex Builder to fix bugs (example) so it's not impossible to do if you have the time and knowledge.

Ryan Lynch
Very interesting technique, thanks for sharing!
macke