i am currently on a job using a large open source shopping cart framework.
there has been lots of customization done, plugins added etc. so of course there are errors and what not.

one plugin add-on in particular involved over 160 files! and once added there is now some sort of logic error. here are some questions that come up for me when trying to troubleshoot.

how can a programmer track down where a constant is being defined?
and the same with a functions, how can a function be found amongst 100's of files? is it possible to track variables?

i recently started using Aptana but as of yet don't know how to do the above using it. any advice, help etc. would be much appreciated, thanks!