the search box on the left of the repo display when you're looking at the files in the repo...
but i search on my local storage since i have a copy of the repo for using to build my FG... using find and grep on the local system is much easier and faster... plus i can then also take my time and try to read the code to understand it... maybe even tossing in some debug log lines so i can maybe see what's happening here and there as the code runs...