Just a reminder, for when you do an "svn update". If, in the left column, in addition to U and G, you see any A or D for added or deleted files, then you will need to regenerate the dependency list.
Also, at link time, if you see errors about missing symbols, then you probably have too many or too few .o files in the /build/obj directory. This is another clue that you need to refresh the dependency cache.
The "clean" target has a task for deleting build.dep, so "btool clean" always works, if all else fails and you need to take drastic measures.
Another trick: if you need to force a rebuild of a certain set of files, but don't want to rebuild the whole tree, then look in /build/obj. The directory structure mirrors /src. Just delete the corresponding .o's and run btool again.
bob