The Advanced Search feature provides search functionality for all elements within a Games script. You can access it via a keyboard shortcut (Ctrl+Shift+F / ⌘+Shift+F), by clicking the magnifying glass icon located in the lower toolbar or from the Edit menu.
Advanced Search will retain results from previous searches when you dismiss and re-open it:
Search results can be filtered by match Type:
You can also get more specific with your searches to help narrow down the search results by using Case Sensitive results, and/or an exact string using Whole Words.