From lazarus, suggest you use Ctrl-Shift-F -> Find in files and give [procedurename] and specify the correct Directories where to search. On win10 it is quite slow the first time, but subsequent searches are much faster.
In the search results, locate what unit seems to be concerned, click on one of the retrieved [procedurename] (not the filename). That should help you to navigate the sources without using grep.
Lazarus quite recent trunk (+/- changes regarding TScrollBar, IntitalSetupDialog, Options.Environment options). FPC 3.0.4 (the mac os one) in 32 bit mode from svn + some mods.
Windows 10 Pro x64 (v. 1903 / 18362.418) and for occasional Linux tests, Manjaro (QT5 and GTK2)