The "Unused Symbols" report shows an interactive listing of all subs/functions, variables, types, fields, and constants that appear to not be used after being declared or dimensioned. No other FB editor has this functionality because it entailed a few more hooks into the actual FBC parser. It needs more testing to verify its accuracy and you still need to use judgement because even though a symbol is not used doesn't mean that it is not important and probably should remain (eg. function declares in a .bi include file).
Clicking on a line in the report takes you to the source code. The report automatically refreshes with up to date line numbering once the background parsing thread completes (usually within a second).